After a decade or extra the place Single-Web page-Purposes generated by
JavaScript frameworks have
grow to be the norm, we see that server-side rendered HTML is changing into
well-liked once more, additionally due to libraries corresponding to HTMX or Turbo. Writing a wealthy net UI in a
historically server-side language like Go or Java is no longer simply attainable,
however a really enticing proposition.
We then face the issue of write automated exams for the HTML
components of our net purposes. Whereas the JavaScript world has advanced highly effective and complex methods to check the UI,
ranging in dimension from unit-level to integration to end-to-end, in different
languages we wouldn’t have such a richness of instruments accessible.
When writing an online utility in Go or Java, HTML is usually generated
by means of templates, which comprise small fragments of logic. It’s definitely
attainable to check them not directly by means of end-to-end exams, however these exams
are gradual and costly.
We will as an alternative write unit exams that use CSS selectors to probe the
presence and proper content material of particular HTML components inside a doc.
Parameterizing these exams makes it simple so as to add new exams and to obviously
point out what particulars every check is verifying. This strategy works with any
language that has entry to an HTML parsing library that helps CSS
selectors; examples are supplied in Go and Java.
Degree 1: checking for sound HTML
The primary factor we wish to verify is that the HTML we produce is
mainly sound. I do not imply to verify that HTML is legitimate in accordance with the
W3C; it could be cool to do it, but it surely’s higher to begin with a lot easier and quicker checks.
As an example, we would like our exams to
break if the template generates one thing like
<div>foo</p>
Let’s examine do it in phases: we begin with the next check that
tries to compile the template. In Go we use the usual html/template bundle.
Go
func Test_wellFormedHtml(t *testing.T)
templ := template.Should(template.ParseFiles("index.tmpl"))
_ = templ
In Java, we use jmustache
as a result of it is quite simple to make use of; Freemarker or
Velocity are different frequent selections.
Java
@Take a look at
void indexIsSoundHtml()
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream("/index.tmpl")));
If we run this check, it would fail, as a result of the index.tmpl file does
not exist. So we create it, with the above damaged HTML. Now the check ought to move.
Then we create a mannequin for the template to make use of. The appliance manages a todo-list, and
we are able to create a minimal mannequin for demonstration functions.
Go
func Test_wellFormedHtml(t *testing.T)
templ := template.Should(template.ParseFiles("index.tmpl"))
mannequin := todo.NewList()
_ = templ
_ = mannequin
Java
@Take a look at
void indexIsSoundHtml()
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream("/index.tmpl")));
var mannequin = new TodoList();
Now we render the template, saving the leads to a bytes buffer (Go) or as a String (Java).
Go
func Test_wellFormedHtml(t *testing.T)
templ := template.Should(template.ParseFiles("index.tmpl"))
mannequin := todo.NewList()
var buf bytes.Buffer
err := templ.Execute(&buf, mannequin)
if err != nil
panic(err)
Java
@Take a look at
void indexIsSoundHtml()
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream("/index.tmpl")));
var mannequin = new TodoList();
var html = template.execute(mannequin);
At this level, we wish to parse the HTML and we anticipate to see an
error, as a result of in our damaged HTML there’s a div component that
is closed by a p component. There’s an HTML parser within the Go
commonplace library, however it’s too lenient: if we run it on our damaged HTML, we do not get an
error. Fortunately, the Go commonplace library additionally has an XML parser that may be
configured to parse HTML (due to this Stack Overflow reply)
Go
func Test_wellFormedHtml(t *testing.T)
templ := template.Should(template.ParseFiles("index.tmpl"))
mannequin := todo.NewList()
// render the template right into a buffer
var buf bytes.Buffer
err := templ.Execute(&buf, mannequin)
if err != nil
panic(err)
// verify that the template could be parsed as (lenient) XML
decoder := xml.NewDecoder(bytes.NewReader(buf.Bytes()))
decoder.Strict = false
decoder.AutoClose = xml.HTMLAutoClose
decoder.Entity = xml.HTMLEntity
for
_, err := decoder.Token()
swap err
case io.EOF:
return // We're executed, it is legitimate!
case nil:
// do nothing
default:
t.Fatalf("Error parsing html: %s", err)
supply
This code configures the HTML parser to have the fitting stage of leniency
for HTML, after which parses the HTML token by token. Certainly, we see the error
message we needed:
--- FAIL: Test_wellFormedHtml (0.00s)
index_template_test.go:61: Error parsing html: XML syntax error on line 4: surprising finish component </p>
In Java, a flexible library to make use of is jsoup:
Java
@Take a look at
void indexIsSoundHtml()
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream("/index.tmpl")));
var mannequin = new TodoList();
var html = template.execute(mannequin);
var parser = Parser.htmlParser().setTrackErrors(10);
Jsoup.parse(html, "", parser);
assertThat(parser.getErrors()).isEmpty();
supply
And we see it fail:
java.lang.AssertionError: Anticipating empty however was:<[<1:13>: Unexpected EndTag token [</p>] when in state [InBody],
Success! Now if we copy over the contents of the TodoMVC
template to our index.tmpl file, the check passes.
The check, nevertheless, is simply too verbose: we extract two helper features, in
order to make the intention of the check clearer, and we get
Go
func Test_wellFormedHtml(t *testing.T)
mannequin := todo.NewList()
buf := renderTemplate("index.tmpl", mannequin)
assertWellFormedHtml(t, buf)
supply
Java
@Take a look at
void indexIsSoundHtml()
var mannequin = new TodoList();
var html = renderTemplate("/index.tmpl", mannequin);
assertSoundHtml(html);
supply
Degree 2: testing HTML construction
What else ought to we check?
We all know that the appears to be like of a web page can solely be examined, finally, by a
human taking a look at how it’s rendered in a browser. Nevertheless, there may be typically
logic in templates, and we would like to have the ability to check that logic.
One could be tempted to check the rendered HTML with string equality,
however this system fails in apply, as a result of templates comprise numerous
particulars that make string equality assertions impractical. The assertions
grow to be very verbose, and when studying the assertion, it turns into tough
to know what it’s that we’re making an attempt to show.
What we want
is a way to claim that some components of the rendered HTML
correspond to what we anticipate, and to ignore all the small print we do not
care about. A technique to do that is by working queries with the CSS selector language:
it’s a highly effective language that enables us to pick out the
components that we care about from the entire HTML doc. As soon as we now have
chosen these components, we (1) rely that the variety of component returned
is what we anticipate, and (2) that they comprise the textual content or different content material
that we anticipate.
The UI that we’re speculated to generate appears to be like like this:
There are a number of particulars which might be rendered dynamically:
- The variety of gadgets and their textual content content material change, clearly
- The fashion of the todo-item adjustments when it is accomplished (e.g., the
second) - The “2 gadgets left” textual content will change with the variety of non-completed
gadgets - One of many three buttons “All”, “Lively”, “Accomplished” shall be
highlighted, relying on the present url; for example if we determine that the
url that exhibits solely the “Lively” gadgets is/lively, then when the present url
is/lively, the “Lively” button ought to be surrounded by a skinny purple
rectangle - The “Clear accomplished” button ought to solely be seen if any merchandise is
accomplished
Every of this considerations could be examined with the assistance of CSS selectors.
This can be a snippet from the TodoMVC template (barely simplified). I
haven’t but added the dynamic bits, so what we see right here is static
content material, supplied for instance:
index.tmpl
<part class="todoapp">
<ul class="todo-list">
<!-- These are right here simply to point out the construction of the listing gadgets -->
<!-- Listing gadgets ought to get the category `accomplished` when marked as accomplished -->
<li class="accomplished"> ②
<div class="view">
<enter class="toggle" sort="checkbox" checked>
<label>Style JavaScript</label> ①
<button class="destroy"></button>
</div>
</li>
<li>
<div class="view">
<enter class="toggle" sort="checkbox">
<label>Purchase a unicorn</label> ①
<button class="destroy"></button>
</div>
</li>
</ul>
<footer class="footer">
<!-- This ought to be `0 gadgets left` by default -->
<span class="todo-count"><sturdy>0</sturdy> merchandise left</span> ⓷
<ul class="filters">
<li>
<a class="chosen" href="#/">All</a> ④
</li>
<li>
<a href="#/lively">Lively</a>
</li>
<li>
<a href="#/accomplished">Accomplished</a>
</li>
</ul>
<!-- Hidden if no accomplished gadgets are left ↓ -->
<button class="clear-completed">Clear accomplished</button> ⑤
</footer>
</part>
supply
By trying on the static model of the template, we are able to deduce which
CSS selectors can be utilized to determine the related components for the 5 dynamic
options listed above:
| function | CSS selector | |
|---|---|---|
| ① | All of the gadgets | ul.todo-list li |
| ② | Accomplished gadgets | ul.todo-list li.accomplished |
| ⓷ | Gadgets left | span.todo-count |
| ④ | Highlighted navigation hyperlink | ul.filters a.chosen |
| ⑤ | Clear accomplished button | button.clear-completed |
We will use these selectors to focus our exams on simply the issues we wish to check.
Testing HTML content material
The primary check will search for all of the gadgets, and show that the info
arrange by the check is rendered accurately.
func Test_todoItemsAreShown(t *testing.T)
mannequin := todo.NewList()
mannequin.Add("Foo")
mannequin.Add("Bar")
buf := renderTemplate(mannequin)
// assert there are two <li> components contained in the <ul class="todo-list">
// assert the primary <li> textual content is "Foo"
// assert the second <li> textual content is "Bar"
We’d like a solution to question the HTML doc with our CSS selector; a very good
library for Go is goquery, that implements an API impressed by jQuery.
In Java, we hold utilizing the identical library we used to check for sound HTML, specifically
jsoup. Our check turns into:
Go
func Test_todoItemsAreShown(t *testing.T)
mannequin := todo.NewList()
mannequin.Add("Foo")
mannequin.Add("Bar")
buf := renderTemplate("index.tmpl", mannequin)
// parse the HTML with goquery
doc, err := goquery.NewDocumentFromReader(bytes.NewReader(buf.Bytes()))
if err != nil
// if parsing fails, we cease the check right here with t.FatalF
t.Fatalf("Error rendering template %s", err)
// assert there are two <li> components contained in the <ul class="todo-list">
choice := doc.Discover("ul.todo-list li")
assert.Equal(t, 2, choice.Size())
// assert the primary <li> textual content is "Foo"
assert.Equal(t, "Foo", textual content(choice.Nodes[0]))
// assert the second <li> textual content is "Bar"
assert.Equal(t, "Bar", textual content(choice.Nodes[1]))
func textual content(node *html.Node) string
// A little bit mess as a result of the truth that goquery has
// a .Textual content() methodology on Choice however not on html.Node
sel := goquery.SelectionNodes: []*html.Nodenode
return strings.TrimSpace(sel.Textual content())
supply
Java
@Take a look at
void todoItemsAreShown() throws IOException
var mannequin = new TodoList();
mannequin.add("Foo");
mannequin.add("Bar");
var html = renderTemplate("/index.tmpl", mannequin);
// parse the HTML with jsoup
Doc doc = Jsoup.parse(html, "");
// assert there are two <li> components contained in the <ul class="todo-list">
var choice = doc.choose("ul.todo-list li");
assertThat(choice).hasSize(2);
// assert the primary <li> textual content is "Foo"
assertThat(choice.get(0).textual content()).isEqualTo("Foo");
// assert the second <li> textual content is "Bar"
assertThat(choice.get(1).textual content()).isEqualTo("Bar");
supply
If we nonetheless have not modified the template to populate the listing from the
mannequin, this check will fail, as a result of the static template
todo gadgets have completely different textual content:
Go
--- FAIL: Test_todoItemsAreShown (0.00s)
index_template_test.go:44: First listing merchandise: need Foo, acquired Style JavaScript
index_template_test.go:49: Second listing merchandise: need Bar, acquired Purchase a unicorn
Java
IndexTemplateTest > todoItemsAreShown() FAILED
org.opentest4j.AssertionFailedError:
Anticipating:
<"Style JavaScript">
to be equal to:
<"Foo">
however was not.
We repair it by making the template use the mannequin knowledge:
Go
<ul class="todo-list"> vary .Gadgets <li> <div class="view"> <enter class="toggle" sort="checkbox"> <label> .Title </label> <button class="destroy"></button> </div> </li> finish </ul>
supply
Java – jmustache
<ul class="todo-list"> #allItems <li> <div class="view"> <enter class="toggle" sort="checkbox"> <label> title </label> <button class="destroy"></button> </div> </li> /allItems </ul>
supply
Take a look at each content material and soundness on the identical time
Our check works, however it’s a bit verbose, particularly the Go model. If we will have extra
exams, they may grow to be repetitive and tough to learn, so we make it extra concise by extracting a helper perform for parsing the html. We additionally take away the
feedback, because the code ought to be clear sufficient
Go
func Test_todoItemsAreShown(t *testing.T)
mannequin := todo.NewList()
mannequin.Add("Foo")
mannequin.Add("Bar")
buf := renderTemplate("index.tmpl", mannequin)
doc := parseHtml(t, buf)
choice := doc.Discover("ul.todo-list li")
assert.Equal(t, 2, choice.Size())
assert.Equal(t, "Foo", textual content(choice.Nodes[0]))
assert.Equal(t, "Bar", textual content(choice.Nodes[1]))
func parseHtml(t *testing.T, buf bytes.Buffer) *goquery.Doc
doc, err := goquery.NewDocumentFromReader(bytes.NewReader(buf.Bytes()))
if err != nil
// if parsing fails, we cease the check right here with t.FatalF
t.Fatalf("Error rendering template %s", err)
return doc
Java
@Take a look at
void todoItemsAreShown() throws IOException
var mannequin = new TodoList();
mannequin.add("Foo");
mannequin.add("Bar");
var html = renderTemplate("/index.tmpl", mannequin);
var doc = parseHtml(html);
var choice = doc.choose("ul.todo-list li");
assertThat(choice).hasSize(2);
assertThat(choice.get(0).textual content()).isEqualTo("Foo");
assertThat(choice.get(1).textual content()).isEqualTo("Bar");
non-public static Doc parseHtml(String html)
return Jsoup.parse(html, "");
Significantly better! A minimum of in my view. Now that we extracted the parseHtml helper, it is
a good suggestion to verify for sound HTML within the helper:
Go
func parseHtml(t *testing.T, buf bytes.Buffer) *goquery.Doc
assertWellFormedHtml(t, buf)
doc, err := goquery.NewDocumentFromReader(bytes.NewReader(buf.Bytes()))
if err != nil
// if parsing fails, we cease the check right here with t.FatalF
t.Fatalf("Error rendering template %s", err)
return doc
supply
Java
non-public static Doc parseHtml(String html) var parser = Parser.htmlParser().setTrackErrors(10); var doc = Jsoup.parse(html, "", parser); assertThat(parser.getErrors()).isEmpty(); return doc;
supply
And with this, we are able to do away with the primary check that we wrote, as we at the moment are testing for sound HTML on a regular basis.
The second check
Now we’re in a very good place for testing extra rendering logic. The
second dynamic function in our listing is “Listing gadgets ought to get the category
accomplished when marked as accomplished”. We will write a check for this:
Go
func Test_completedItemsGetCompletedClass(t *testing.T)
mannequin := todo.NewList()
mannequin.Add("Foo")
mannequin.AddCompleted("Bar")
buf := renderTemplate("index.tmpl", mannequin)
doc := parseHtml(t, buf)
choice := doc.Discover("ul.todo-list li.accomplished")
assert.Equal(t, 1, choice.Measurement())
assert.Equal(t, "Bar", textual content(choice.Nodes[0]))
supply
Java
@Take a look at
void completedItemsGetCompletedClass()
var mannequin = new TodoList();
mannequin.add("Foo");
mannequin.addCompleted("Bar");
var html = renderTemplate("/index.tmpl", mannequin);
Doc doc = Jsoup.parse(html, "");
var choice = doc.choose("ul.todo-list li.accomplished");
assertThat(choice).hasSize(1);
assertThat(choice.textual content()).isEqualTo("Bar");
supply
And this check could be made inexperienced by including this little bit of logic to the
template:
Go
<ul class="todo-list">
vary .Gadgets
<li class=" if .IsCompleted accomplished finish ">
<div class="view">
<enter class="toggle" sort="checkbox">
<label> .Title </label>
<button class="destroy"></button>
</div>
</li>
finish
</ul>
supply
Java – jmustache
<ul class="todo-list">
#allItems
<li class=" #isCompleted accomplished /isCompleted ">
<div class="view">
<enter class="toggle" sort="checkbox">
<label> title </label>
<button class="destroy"></button>
</div>
</li>
/allItems
</ul>
supply
So little by little, we are able to check and add the varied dynamic options
that our template ought to have.
Make it simple so as to add new exams
The primary of the 20 suggestions from the wonderful discuss by Russ Cox on Go
Testing is “Make it simple so as to add new check instances“. Certainly, in Go there
is a bent to make most exams parameterized, for this very purpose.
Alternatively, whereas Java has
good help
for parameterized exams with JUnit 5, they aren’t used as a lot.
Since our present two exams have the identical construction, we
might issue them right into a single parameterized check.
A check case for us will include:
- A reputation (in order that we are able to produce clear error messages when the check
fails) - A mannequin (in our case a
todo.Listing) - A CSS selector
- A listing of textual content matches that we look forward to finding after we run the CSS
selector on the rendered HTML.
So that is the info construction for our check instances:
Go
var testCases = []struct
identify string
mannequin *todo.Listing
selector string
matches []string
identify: "all todo gadgets are proven",
mannequin: todo.NewList().
Add("Foo").
Add("Bar"),
selector: "ul.todo-list li",
matches: []string"Foo", "Bar",
,
identify: "accomplished gadgets get the 'accomplished' class",
mannequin: todo.NewList().
Add("Foo").
AddCompleted("Bar"),
selector: "ul.todo-list li.accomplished",
matches: []string"Bar",
,
supply
Java
file TestCase(String identify,
TodoList mannequin,
String selector,
Listing<String> matches)
@Override
public String toString()
return identify;
public static TestCase[] indexTestCases()
return new TestCase[]
new TestCase(
"all todo gadgets are proven",
new TodoList()
.add("Foo")
.add("Bar"),
"ul.todo-list li",
Listing.of("Foo", "Bar")),
new TestCase(
"accomplished gadgets get the 'accomplished' class",
new TodoList()
.add("Foo")
.addCompleted("Bar"),
"ul.todo-list li.accomplished",
Listing.of("Bar")),
;
supply
And that is our parameterized check:
Go
func Test_indexTemplate(t *testing.T)
for _, check := vary testCases
t.Run(check.identify, func(t *testing.T)
buf := renderTemplate("index.tmpl", check.mannequin)
assertWellFormedHtml(t, buf)
doc := parseHtml(t, buf)
choice := doc.Discover(check.selector)
require.Equal(t, len(check.matches), len(choice.Nodes), "surprising # of matches")
for i, node := vary choice.Nodes
assert.Equal(t, check.matches[i], textual content(node))
)
supply
Java
@ParameterizedTest
@MethodSource("indexTestCases")
void testIndexTemplate(TestCase check)
var html = renderTemplate("/index.tmpl", check.mannequin);
var doc = parseHtml(html);
var choice = doc.choose(check.selector);
assertThat(choice).hasSize(check.matches.dimension());
for (int i = 0; i < check.matches.dimension(); i++)
assertThat(choice.get(i).textual content()).isEqualTo(check.matches.get(i));
supply
We will now run our parameterized check and see it move:
Go
$ go check -v === RUN Test_indexTemplate === RUN Test_indexTemplate/all_todo_items_are_shown === RUN Test_indexTemplate/completed_items_get_the_'accomplished'_class --- PASS: Test_indexTemplate (0.00s) --- PASS: Test_indexTemplate/all_todo_items_are_shown (0.00s) --- PASS: Test_indexTemplate/completed_items_get_the_'accomplished'_class (0.00s) PASS okay tdd-html-templates 0.608s
Java
$ ./gradlew check > Activity :check IndexTemplateTest > testIndexTemplate(TestCase) > [1] all todo gadgets are proven PASSED IndexTemplateTest > testIndexTemplate(TestCase) > [2] accomplished gadgets get the 'accomplished' class PASSED
Be aware how, by giving a reputation to our check instances, we get very readable check output, each on the terminal and within the IDE:
Having rewritten our two previous exams in desk kind, it is now tremendous simple so as to add
one other. That is the check for the “x gadgets left” textual content:
Go
identify: "gadgets left",
mannequin: todo.NewList().
Add("One").
Add("Two").
AddCompleted("Three"),
selector: "span.todo-count",
matches: []string"2 gadgets left",
,
supply
Java
new TestCase(
"gadgets left",
new TodoList()
.add("One")
.add("Two")
.addCompleted("Three"),
"span.todo-count",
Listing.of("2 gadgets left")),
supply
And the corresponding change within the html template is:
Go
<span class="todo-count"><sturdy>len .ActiveItems</sturdy> gadgets left</span>
supply
Java – jmustache
<span class="todo-count"><sturdy>activeItemsCount</sturdy> gadgets left</span>
supply
The above change within the template requires a supporting methodology within the mannequin:
Go
sort Merchandise struct
Title string
IsCompleted bool
sort Listing struct
Gadgets []*Merchandise
func (l *Listing) ActiveItems() []*Merchandise
var consequence []*Merchandise
for _, merchandise := vary l.Gadgets
if !merchandise.IsCompleted
consequence = append(consequence, merchandise)
return consequence
supply
Java
public class TodoList
non-public ultimate Listing<TodoItem> gadgets = new ArrayList<>();
// ...
public lengthy activeItemsCount()
return gadgets.stream().filter(TodoItem::isActive).rely();
supply
We have invested slightly effort in our testing infrastructure, in order that including new
check instances is less complicated. Within the subsequent part, we’ll see that the necessities
for the following check instances will push us to refine our check infrastructure additional.
Making the desk extra expressive, on the expense of the check code
We’ll now check the “All”, “Lively” and “Accomplished” navigation hyperlinks at
the underside of the UI (see the image above),
and these depend upon which url we’re visiting, which is
one thing that our template has no solution to discover out.
Presently, all we move to our template is our mannequin, which is a todo-list.
It isn’t appropriate so as to add the presently visited url to the mannequin, as a result of that’s
person navigation state, not utility state.
So we have to move extra info to the template past the mannequin. A simple method
is to move a map, which we assemble in our
renderTemplate perform:
Go
func renderTemplate(mannequin *todo.Listing, path string) bytes.Buffer
templ := template.Should(template.ParseFiles("index.tmpl"))
var buf bytes.Buffer
knowledge := map[string]any
"mannequin": mannequin,
"path": path,
err := templ.Execute(&buf, knowledge)
if err != nil
panic(err)
return buf
Java
non-public String renderTemplate(String templateName, TodoList mannequin, String path)
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream(templateName)));
var knowledge = Map.of(
"mannequin", mannequin,
"path", path
);
return template.execute(knowledge);
And correspondingly our check instances desk has yet one more area:
Go
var testCases = []struct
identify string
mannequin *todo.Listing
path string
selector string
matches []string
identify: "all todo gadgets are proven",
mannequin: todo.NewList().
Add("Foo").
Add("Bar"),
selector: "ul.todo-list li",
matches: []string"Foo", "Bar",
,
// ... the opposite instances
identify: "highlighted navigation hyperlink: All",
path: "/",
selector: "ul.filters a.chosen",
matches: []string"All",
,
identify: "highlighted navigation hyperlink: Lively",
path: "/lively",
selector: "ul.filters a.chosen",
matches: []string"Lively",
,
identify: "highlighted navigation hyperlink: Accomplished",
path: "/accomplished",
selector: "ul.filters a.chosen",
matches: []string"Accomplished",
,
Java
file TestCase(String identify,
TodoList mannequin,
String path,
String selector,
Listing<String> matches)
@Override
public String toString()
return identify;
public static TestCase[] indexTestCases()
return new TestCase[]
new TestCase(
"all todo gadgets are proven",
new TodoList()
.add("Foo")
.add("Bar"),
"/",
"ul.todo-list li",
Listing.of("Foo", "Bar")),
// ... the earlier instances
new TestCase(
"highlighted navigation hyperlink: All",
new TodoList(),
"/",
"ul.filters a.chosen",
Listing.of("All")),
new TestCase(
"highlighted navigation hyperlink: Lively",
new TodoList(),
"/lively",
"ul.filters a.chosen",
Listing.of("Lively")),
new TestCase(
"highlighted navigation hyperlink: Accomplished",
new TodoList(),
"/accomplished",
"ul.filters a.chosen",
Listing.of("Accomplished")),
;
We discover that for the three new instances, the mannequin is irrelevant;
whereas for the earlier instances, the trail is irrelevant. The Go syntax permits us
to initialize a struct with simply the fields we’re all for, however Java doesn’t have
the same function, so we’re pushed to move additional info, and this makes the check instances
desk more durable to know.
A developer would possibly have a look at the primary check case and surprise if the anticipated habits relies upon
on the trail being set to "/", and could be tempted so as to add extra instances with
a unique path. In the identical method, when studying the
highlighted navigation hyperlink check instances, the developer would possibly surprise if the
anticipated habits depends upon the mannequin being set to an empty todo listing. If that’s the case, one would possibly
be led so as to add irrelevant check instances for the highlighted hyperlink with non-empty todo-lists.
We wish to optimize for the time of the builders, so it is worthwhile to keep away from including irrelevant
knowledge to our check case. In Java we’d move null for the
irrelevant fields, however there’s a greater method: we are able to use
the builder sample,
popularized by Joshua Bloch.
We will rapidly write one for the Java TestCase file this fashion:
Java
file TestCase(String identify,
TodoList mannequin,
String path,
String selector,
Listing<String> matches)
@Override
public String toString()
return identify;
public static ultimate class Builder
String identify;
TodoList mannequin;
String path;
String selector;
Listing<String> matches;
public Builder identify(String identify)
this.identify = identify;
return this;
public Builder mannequin(TodoList mannequin)
this.mannequin = mannequin;
return this;
public Builder path(String path)
this.path = path;
return this;
public Builder selector(String selector)
this.selector = selector;
return this;
public Builder matches(String ... matches)
this.matches = Arrays.asList(matches);
return this;
public TestCase construct()
return new TestCase(identify, mannequin, path, selector, matches);
Hand-coding builders is slightly tedious, however doable, although there are
automated methods to put in writing them.
Now we are able to rewrite our Java check instances with the Builder, to
obtain better readability:
Java
public static TestCase[] indexTestCases()
return new TestCase[]
new TestCase.Builder()
.identify("all todo gadgets are proven")
.mannequin(new TodoList()
.add("Foo")
.add("Bar"))
.selector("ul.todo-list li")
.matches("Foo", "Bar")
.construct(),
// ... different instances
new TestCase.Builder()
.identify("highlighted navigation hyperlink: Accomplished")
.path("/accomplished")
.selector("ul.filters a.chosen")
.matches("Accomplished")
.construct(),
;
So, the place are we with our exams? At current, they fail for the mistaken purpose: null-pointer exceptions
as a result of lacking mannequin and path values.
With a view to get our new check instances to fail for the fitting purpose, specifically that the template does
not but have logic to focus on the proper hyperlink, we should
present default values for mannequin and path. In Go, we are able to do that
within the check methodology:
Go
func Test_indexTemplate(t *testing.T)
for _, check := vary testCases
t.Run(check.identify, func(t *testing.T)
if check.mannequin == nil
check.mannequin = todo.NewList()
buf := renderTemplate(check.mannequin, check.path)
// ... identical as earlier than
)
supply
In Java, we are able to present default values within the builder:
Java
public static ultimate class Builder
String identify;
TodoList mannequin = new TodoList();
String path = "/";
String selector;
Listing<String> matches;
// ...
supply
With these adjustments, we see that the final two check instances, those for the highlighted hyperlink Lively
and Accomplished fail, for the anticipated purpose that the highlighted hyperlink doesn’t change:
Go
=== RUN Test_indexTemplate/highlighted_navigation_link:_Active
index_template_test.go:82:
Error Hint: .../tdd-templates/go/index_template_test.go:82
Error: Not equal:
anticipated: "Lively"
precise : "All"
=== RUN Test_indexTemplate/highlighted_navigation_link:_Completed
index_template_test.go:82:
Error Hint: .../tdd-templates/go/index_template_test.go:82
Error: Not equal:
anticipated: "Accomplished"
precise : "All"
Java
IndexTemplateTest > testIndexTemplate(TestCase) > [5] highlighted navigation hyperlink: Lively FAILED
org.opentest4j.AssertionFailedError:
Anticipating:
<"All">
to be equal to:
<"Lively">
however was not.
IndexTemplateTest > testIndexTemplate(TestCase) > [6] highlighted navigation hyperlink: Accomplished FAILED
org.opentest4j.AssertionFailedError:
Anticipating:
<"All">
to be equal to:
<"Accomplished">
however was not.
To make the exams move, we make these adjustments to the template:
Go
<ul class="filters">
<li>
<a class=" if eq .path "/" chosen finish " href="#/">All</a>
</li>
<li>
<a class=" if eq .path "/lively" chosen finish " href="#/lively">Lively</a>
</li>
<li>
<a class=" if eq .path "/accomplished" chosen finish " href="#/accomplished">Accomplished</a>
</li>
</ul>
supply
Java – jmustache
<ul class="filters">
<li>
<a class=" #pathRoot chosen /pathRoot " href="#/">All</a>
</li>
<li>
<a class=" #pathActive chosen /pathActive " href="#/lively">Lively</a>
</li>
<li>
<a class=" #pathCompleted chosen /pathCompleted " href="#/accomplished">Accomplished</a>
</li>
</ul>
supply
For the reason that Mustache template language doesn’t enable for equality testing, we should change the
knowledge handed to the template in order that we execute the equality exams earlier than rendering the template:
Java
non-public String renderTemplate(String templateName, TodoList mannequin, String path)
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream(templateName)));
var knowledge = Map.of(
"mannequin", mannequin,
"pathRoot", path.equals("/"),
"pathActive", path.equals("/lively"),
"pathCompleted", path.equals("/accomplished")
);
return template.execute(knowledge);
supply
And with these adjustments, all of our exams now move.
To recap this part, we made the check code slightly bit extra sophisticated, in order that the check
instances are clearer: this can be a excellent tradeoff!
Degree 3: testing HTML behaviour
Within the story to date, we examined the behaviour of the HTML
templates, by checking the construction of the generated HTML.
That is good, however what if we needed to check the behaviour of the HTML
itself, plus any CSS and JavaScript it might use?
The behaviour of HTML by itself is often fairly apparent, as a result of
there may be not a lot of it. The one components that may work together with the
person are the anchor (<a>), <kind> and
<enter> components, however the image adjustments fully when
we add CSS, that may disguise, present, transfer round issues and much extra, and
with JavaScript, that may add any behaviour to a web page.
In an utility that’s primarily rendered server-side, we anticipate
that the majority behaviour is applied by returning new HTML with a
round-trip to the person, and this may be examined adequately with the
methods we have seen to date, however what if we needed to hurry up the
utility behaviour with a library corresponding to HTMX? This library works by means of particular
attributes which might be added to components so as to add Ajax behaviour. These
attributes are in impact a DSL that we’d wish to
check.
How can we check the mix of HTML, CSS and JavaScript in
a unit check?
Testing HTML, CSS and JavaScript requires one thing that is ready to
interpret and execute their behaviours; in different phrases, we want a
browser! It’s customary to make use of headless browsers in end-to-end exams;
can we use them for unitary exams as an alternative? I feel that is attainable,
utilizing the next methods, though I need to admit I’ve but to strive
this on an actual venture.
We’ll use the Playwright
library, that’s accessible for each Go and
Java. The exams we
are going to put in writing shall be slower, as a result of we should wait a number of
seconds for the headless browser to begin, however will retain among the
vital traits of unit exams, primarily that we’re testing
simply the HTML (and any related CSS and JavaScript), in isolation from
another server-side logic.
Persevering with with the TodoMVC
instance, the following factor we’d wish to check is what occurs when the
person clicks on the checkbox of a todo merchandise. What we would prefer to occur is
that:
- A POST name to the server is made, in order that the appliance is aware of
that the state of a todo merchandise has modified - The server returns new HTML for the dynamic a part of the web page,
specifically all the part with class “todoapp”, in order that we are able to present the
new state of the appliance together with the rely of remaining “lively”
gadgets (see the template above) - The web page replaces the previous contents of the “todoapp” part with
the brand new ones.
Loading the web page within the Playwright browser
We begin with a check that can simply load the preliminary HTML. The check
is slightly concerned, so I present the entire code right here, after which I’ll
remark it little by little.
Go
func Test_toggleTodoItem(t *testing.T)
// render the preliminary HTML
mannequin := todo.NewList().
Add("One").
Add("Two")
initialHtml := renderTemplate("index.tmpl", mannequin, "/")
// open the browser web page with Playwright
web page := openPage()
defer web page.Shut()
logActivity(web page)
// stub community calls
err := web page.Route("**", func(route playwright.Route)
if route.Request().URL() == "http://localhost:4567/index.html"
// serve the preliminary HTML
stubResponse(route, initialHtml.String(), "textual content/html")
else
// keep away from surprising requests
panic("surprising request: " + route.Request().URL())
)
if err != nil
t.Deadly(err)
// load preliminary HTML within the web page
response, err := web page.Goto("http://localhost:4567/index.html")
if err != nil
t.Deadly(err)
if response.Standing() != 200
t.Fatalf("surprising standing: %d", response.Standing())
supply
Java
public class IndexBehaviourTest {
static Playwright playwright;
static Browser browser;
@BeforeAll
static void launchBrowser()
playwright = Playwright.create();
browser = playwright.chromium().launch();
@AfterAll
static void closeBrowser()
playwright.shut();
@Take a look at
void toggleTodoItem()
// Render the preliminary html
TodoList mannequin = new TodoList()
.add("One")
.add("Two");
String initialHtml = renderTemplate("/index.tmpl", mannequin, "/");
strive (Web page web page = browser.newPage())
logActivity(web page);
// stub community calls
web page.route("**", route ->
if (route.request().url().equals("http://localhost:4567/index.html"))
// serve the preliminary HTML
route.fulfill(new Route.FulfillOptions()
.setContentType("textual content/html")
.setBody(initialHtml));
else
// we do not need surprising calls
fail(String.format("Sudden request: %s %s", route.request().methodology(), route.request().url()));
);
// load preliminary html
web page.navigate("http://localhost:4567/index.html");
}
supply
Firstly of the check, we initialize the mannequin with two todo
gadgets “One” and “Two”, then we render the template as earlier than:
Go
mannequin := todo.NewList().
Add("One").
Add("Two")
initialHtml := renderTemplate("index.tmpl", mannequin, "/")
Java
TodoList mannequin = new TodoList()
.add("One")
.add("Two");
String initialHtml = renderTemplate("/index.tmpl", mannequin, "/");
Then we open the Playwright “web page”, which is able to begin a headless
browser
Go
web page := openPage() defer web page.Shut() logActivity(web page)
Java
strive (Web page web page = browser.newPage())
logActivity(web page);
The openPage perform in Go returns a Playwright
Web page object,
Go
func openPage() playwright.Web page
pw, err := playwright.Run()
if err != nil
log.Fatalf("couldn't begin playwright: %v", err)
browser, err := pw.Chromium.Launch()
if err != nil
log.Fatalf("couldn't launch browser: %v", err)
web page, err := browser.NewPage()
if err != nil
log.Fatalf("couldn't create web page: %v", err)
return web page
and the logActivity perform gives suggestions on what
the web page is doing
Go
func logActivity(web page playwright.Web page)
web page.OnRequest(func(request playwright.Request)
log.Printf(">> %s %sn", request.Technique(), request.URL())
)
web page.OnResponse(func(response playwright.Response)
log.Printf("<< %d %sn", response.Standing(), response.URL())
)
web page.OnLoad(func(web page playwright.Web page)
log.Println("Loaded: " + web page.URL())
)
web page.OnConsole(func(message playwright.ConsoleMessage)
log.Println("! " + message.Textual content())
)
Java
non-public void logActivity(Web page web page)
web page.onRequest(request -> System.out.printf(">> %s %spercentn", request.methodology(), request.url()));
web page.onResponse(response -> System.out.printf("<< %s %spercentn", response.standing(), response.url()));
web page.onLoad(page1 -> System.out.println("Loaded: " + page1.url()));
web page.onConsoleMessage(consoleMessage -> System.out.println("! " + consoleMessage.textual content()));
Then we stub all community exercise that the web page would possibly attempt to do
Go
err := web page.Route("**", func(route playwright.Route)
if route.Request().URL() == "http://localhost:4567/index.html"
// serve the preliminary HTML
stubResponse(route, initialHtml.String(), "textual content/html")
else
// keep away from surprising requests
panic("surprising request: " + route.Request().URL())
)
Java
// stub community calls
web page.route("**", route ->
if (route.request().url().equals("http://localhost:4567/index.html"))
// serve the preliminary HTML
route.fulfill(new Route.FulfillOptions()
.setContentType("textual content/html")
.setBody(initialHtml));
else
// we do not need surprising calls
fail(String.format("Sudden request: %s %s", route.request().methodology(), route.request().url()));
);
and we ask the web page to load the preliminary HTML
Go
response, err := web page.Goto("http://localhost:4567/index.html")
Java
web page.navigate("http://localhost:4567/index.html");
With all this equipment in place, we run the check; it succeeds and
it logs the stubbed community exercise on commonplace output:
Go
=== RUN Test_toggleTodoItem >> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html Loaded: http://localhost:4567/index.html --- PASS: Test_toggleTodoItem (0.89s)
Java
IndexBehaviourTest > toggleTodoItem() STANDARD_OUT
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
Loaded: http://localhost:4567/index.html
IndexBehaviourTest > toggleTodoItem() PASSED
So with this check we at the moment are in a position to load arbitrary HTML in a
headless browser. Within the subsequent sections we’ll see simulate person
interplay with components of the web page, and observe the web page’s
behaviour. However first we have to resolve an issue with the dearth of
identifiers in our area mannequin.
Figuring out todo gadgets
Now we wish to click on on the “One” checkbox. The issue we now have is
that at current, we now have no solution to determine particular person todo gadgets, so
we introduce an Id area within the todo merchandise:
Go – up to date mannequin with Id
sort Merchandise struct Id int Title string IsCompleted bool func (l *Listing) AddWithId(id int, title string) *Listing merchandise := Merchandise Id: id, Title: title, l.Gadgets = append(l.Gadgets, &merchandise) return l // Add creates a brand new todo.Merchandise with a random Id func (l *Listing) Add(title string) *Listing merchandise := Merchandise Id: generateRandomId(), Title: title, l.Gadgets = append(l.Gadgets, &merchandise) return l func generateRandomId() int return abs(rand.Int())
Java – up to date mannequin with Id
public class TodoList
non-public ultimate Listing<TodoItem> gadgets = new ArrayList<>();
public TodoList add(String title)
gadgets.add(new TodoItem(generateRandomId(), title, false));
return this;
public TodoList addCompleted(String title)
gadgets.add(new TodoItem(generateRandomId(), title, true));
return this;
public TodoList add(int id, String title)
gadgets.add(new TodoItem(id, title, false));
return this;
non-public static int generateRandomId()
return new Random().nextInt(0, Integer.MAX_VALUE);
public file TodoItem(int id, String title, boolean isCompleted)
public boolean isActive()
return !isCompleted;
And we replace the mannequin in our check so as to add specific Ids
Go – including Id within the check knowledge
func Test_toggleTodoItem(t *testing.T)
// render the preliminary HTML
mannequin := todo.NewList().
AddWithId(101, "One").
AddWithId(102, "Two")
initialHtml := renderTemplate("index.tmpl", mannequin, "/")
// ...
Java – including Id within the check knowledge
@Take a look at
void toggleTodoItem()
// Render the preliminary html
TodoList mannequin = new TodoList()
.add(101, "One")
.add(102, "Two");
String initialHtml = renderTemplate("/index.tmpl", mannequin, "/");
We at the moment are prepared to check person interplay with the web page.
Clicking on a todo merchandise
We wish to simulate person interplay with the HTML web page. It could be
tempting to proceed to make use of CSS selectors to determine the precise
checkbox that we wish to click on, however there’s a greater method: there’s a
consensus amongst front-end builders that the easiest way to check
interplay with a web page is to make use of it
the identical method that customers do. As an example, you do not search for a
button by means of a CSS locator corresponding to button.purchase; as an alternative,
you search for one thing clickable with the label “Purchase”. In apply,
this implies figuring out components of the web page by means of their
ARIA roles.
To this finish, we add code to our check to search for a checkbox labelled
“One”:
Go
func Test_toggleTodoItem(t *testing.T)
// ...
// click on on the "One" checkbox
checkbox := web page.GetByRole(*playwright.AriaRoleCheckbox, playwright.PageGetByRoleOptionsIdentify: "One")
if err := checkbox.Click on(); err != nil
t.Deadly(err)
Java
@Take a look at
void toggleTodoItem()
// ...
// click on on the "One" checkbox
var checkbox = web page.getByRole(AriaRole.CHECKBOX, new Web page.GetByRoleOptions().setName("One"));
checkbox.click on();
We run the check, and it fails:
Go
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
Loaded: http://localhost:4567/index.html
--- FAIL: Test_toggleTodoItem (32.74s)
index_behaviour_test.go:50: playwright: timeout: Timeout 30000ms exceeded.
Java
IndexBehaviourTest > toggleTodoItem() STANDARD_OUT
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
Loaded: http://localhost:4567/index.html
IndexBehaviourTest > toggleTodoItem() FAILED
com.microsoft.playwright.TimeoutError: Error
message="hyperlink the label to the checkbox correctly:
generated HTML with unhealthy accessibility
<li>
<div class="view">
<enter class="toggle" sort="checkbox">
<label>One</label>
<button class="destroy"></button>
</div>
</li>
We repair it by utilizing the for attribute within the
template,
index.tmpl – Go
<li>
<div class="view">
<enter id="checkbox-.Id" class="toggle" sort="checkbox">
<label for="checkbox-.Id">.Title</label>
<button class="destroy"></button>
</div>
</li>
index.tmpl – Java
<li>
<div class="view">
<enter id="checkbox- id " class="toggle" sort="checkbox">
<label for="checkbox- id "> title </label>
<button class="destroy"></button>
</div>
</li>
In order that it generates correct, accessible HTML:
generated HTML with higher accessibility
<li>
<div class="view">
<enter id="checkbox-101" class="toggle" sort="checkbox">
<label for="checkbox-101">One</label>
<button class="destroy"></button>
</div>
</li>
We run once more the check, and it passes.
On this part we noticed how testing the HTML in the identical was as customers
work together with it led us to make use of ARIA roles, which led to bettering
accessibility of our generated HTML. Within the subsequent part, we'll see
check that the press on a todo merchandise triggers a distant name to the
server, that ought to end in swapping part of the present HTML with
the HTML returned by the XHR name.
Spherical-trip to the server
Now we’ll lengthen our check. We inform the check that if name to
POST /toggle/101 is acquired, it ought to return some
stubbed HTML.
Go
else if route.Request().URL() == "http://localhost:4567/toggle/101" && route.Request().Technique() == "POST" // we anticipate {that a} POST /toggle/101 request is made after we click on on the "One" checkbox const stubbedHtml = ` <part class="todoapp"> <p>Stubbed html</p> </part>` stubResponse(route, stubbedHtml, "textual content/html")
Java
else if (route.request().url().equals("http://localhost:4567/toggle/101") && route.request().methodology().equals("POST")) // we anticipate {that a} POST /toggle/101 request is made after we click on on the "One" checkbox String stubbedHtml = """ <part class="todoapp"> <p>Stubbed html</p> </part> """; route.fulfill(new Route.FulfillOptions() .setContentType("textual content/html") .setBody(stubbedHtml));
And we stub the loading of the HTMX library, which we load from a
native file:
Go
else if route.Request().URL() == "https://unpkg.com/htmx.org@1.9.12"
// serve the htmx library
stubResponse(route, readFile("testdata/htmx.min.js"), "utility/javascript")
Go
else if (route.request().url().equals("https://unpkg.com/htmx.org@1.9.12")) {
// serve the htmx library
route.fulfill(new Route.FulfillOptions()
.setContentType("textual content/html")
.setBody(readFile("/htmx.min.js")));
Lastly, we add the expectation that, after we click on the checkbox,
the part of the HTML that comprises many of the utility is
reloaded.
Go
// click on on the "One" checkbox
checkbox := web page.GetByRole(*playwright.AriaRoleCheckbox, playwright.PageGetByRoleOptionsName: "One")
if err := checkbox.Click on(); err != nil
t.Deadly(err)
// verify that the web page has been up to date
doc := parseHtml(t, content material(t, web page))
components := doc.Discover("physique > part.todoapp > p")
assert.Equal(t, "Stubbed html", components.Textual content(), should(web page.Content material()))
java
// click on on the "One" checkbox
var checkbox = web page.getByRole(AriaRole.CHECKBOX, new Web page.GetByRoleOptions().setName("One"));
checkbox.click on();
// verify that the web page has been up to date
var doc = parseHtml(web page.content material());
var components = doc.choose("physique > part.todoapp > p");
assertThat(components.textual content())
.describedAs(web page.content material())
.isEqualTo("Stubbed html");
We run the check, and it fails, as anticipated. With a view to perceive
why precisely it fails, we add to the error message the entire HTML
doc.
Go
assert.Equal(t, "Stubbed html", components.Textual content(), should(web page.Content material()))
Java
assertThat(components.textual content())
.describedAs(web page.content material())
.isEqualTo("Stubbed html");
The error message may be very verbose, however we see that the explanation it
fails is that we do not see the stubbed HTML within the output. This implies
that the web page didn’t make the anticipated XHR name.
Go – Java is comparable
--- FAIL: Test_toggleTodoItem (2.75s)
=== RUN Test_toggleTodoItem
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
Loaded: http://localhost:4567/index.html
index_behaviour_test.go:67:
Error Hint: .../index_behaviour_test.go:67
Error: Not equal:
anticipated: "Stubbed html"
precise : ""
...
Take a look at: Test_toggleTodoItem
Messages: <!DOCTYPE html><html lang="en"><head>
<meta charset="utf-8">
<meta identify="viewport" content material="width=device-width, initial-scale=1">
<title>Template • TodoMVC</title>
<script src="https://unpkg.com/htmx.org@1.9.12"></script>
<physique>
<part class="todoapp">
...
<li class="">
<div class="view">
<enter id="checkbox-101" class="toggle" sort="checkbox">
<label for="checkbox-101">One</label>
<button class="destroy"></button>
</div>
</li>
...
We will make this check move by altering the HTML template to make use of HTMX
to make an XHR name again to the server. First we load the HTMX
library:
index.tmpl
<title>Template • TodoMVC</title>
<script src="https://unpkg.com/htmx.org@1.9.12"></script>
Then we add the HTMX attributes to the checkboxes:
index.tmpl
<enter data-hx-post="/toggle/.Id" data-hx-target="part.todoapp" id="checkbox-.Id" class="toggle" sort="checkbox">
The data-hx-post annotation will make HTMX do a POST
name to the desired url. The data-hx-target tells HTMX
to repeat the HTML returned by the decision, to the component specified by the
part.todoapp CSS locator.
We run once more the check, and it nonetheless fails!
Go – Java is comparable
--- FAIL: Test_toggleTodoItem (2.40s)
=== RUN Test_toggleTodoItem
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
>> GET https://unpkg.com/htmx.org@1.9.12
<< 200 https://unpkg.com/htmx.org@1.9.12
Loaded: http://localhost:4567/index.html
>> POST http://localhost:4567/toggle/101
<< 200 http://localhost:4567/toggle/101
index_behaviour_test.go:67:
Error Hint: .../index_behaviour_test.go:67
Error: Not equal:
anticipated: "Stubbed html"
precise : ""
...
Take a look at: Test_toggleTodoItem
Messages: <!DOCTYPE html><html lang="en"><head>
<meta charset="utf-8">
<meta identify="viewport" content material="width=device-width, initial-scale=1">
<title>Template • TodoMVC</title>
<script src="https://unpkg.com/htmx.org@1.9.12"></script>
...
<physique>
<part class="todoapp"><part class="todoapp">
<p>Stubbed html</p>
</part></part>
...
</physique></html>
The log traces present that the POST name occurred as anticipated, however
examination of the error message exhibits that the HTML construction we
anticipated will not be there: we now have a part.todoapp nested
inside one other. Because of this we’re not utilizing the HTMX annotations
accurately, and exhibits why this sort of check could be beneficial. We add the
lacking annotation
index.tmpl
<enter
data-hx-post="/toggle/.Id"
data-hx-target="part.todoapp"
data-hx-swap="outerHTML"
id="checkbox-.Id"
class="toggle"
sort="checkbox">
The default behaviour of HTMX is to interchange the inside HTML of the
goal component. The data-hx-swap="outerHTML" annotation
tells HTMX to interchange the outer HTML as an alternative.
and we check once more, and this time it passes!
Go
=== RUN Test_toggleTodoItem >> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html >> GET https://unpkg.com/htmx.org@1.9.12 << 200 https://unpkg.com/htmx.org@1.9.12 Loaded: http://localhost:4567/index.html >> POST http://localhost:4567/toggle/101 << 200 http://localhost:4567/toggle/101 --- PASS: Test_toggleTodoItem (1.39s)
Java
IndexBehaviourTest > toggleTodoItem() STANDARD_OUT
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
>> GET https://unpkg.com/htmx.org@1.9.12
<< 200 https://unpkg.com/htmx.org@1.9.12
Loaded: http://localhost:4567/index.html
>> POST http://localhost:4567/toggle/101
<< 200 http://localhost:4567/toggle/101
IndexBehaviourTest > toggleTodoItem() PASSED
On this part we noticed write a check for the behaviour of our
HTML that, whereas utilizing the sophisticated equipment of a headless browser,
nonetheless feels extra like a unit check than an integration check. It’s in
reality testing simply an HTML web page with any related CSS and JavaScript,
in isolation from different components of the appliance corresponding to controllers,
providers or repositories.
The check prices 2-3 seconds of ready time for the headless browser to come back up, which is often an excessive amount of for a unit check; nevertheless, like a unit check, it is extremely secure, as it’s not flaky, and its failures are documented with a comparatively clear error message.
See the ultimate model of the check in Go and in Java.
Bonus stage: Stringly asserted
Esko Luontola, TDD skilled and writer of the web course tdd.mooc.fi, urged a substitute for testing HTML with CSS selectors: the thought is to rework HTML right into a human-readable canonical kind.
Let’s take for instance this snippet of generated HTML:
<ul class="todo-list">
<li class="">
<div class="view">
<enter id="checkbox-100" class="toggle" sort="checkbox">
<label for="checkbox-100">One</label>
<button class="destroy"></button>
</div>
</li>
<li class="">
<div class="view">
<enter id="checkbox-200" class="toggle" sort="checkbox">
<label for="checkbox-200">Two</label>
<button class="destroy"></button>
</div>
</li>
<li class="accomplished">
<div class="view">
<enter id="checkbox-300" class="toggle" sort="checkbox">
<label for="checkbox-300">Three</label>
<button class="destroy"></button>
</div>
</li>
</ul>
We might visualize the above HTML by:
- deleting all HTML tags
- lowering each sequence of whitespace characters to a single clean
to reach at:
One Two Three
This, nevertheless, removes an excessive amount of of the HTML construction to be helpful. As an example, it doesn’t allow us to distinguish between lively and accomplished gadgets. Some HTML component symbolize seen content material: for example
<enter worth="foo" />
exhibits a textual content field with the phrase “foo” that is a vital a part of the method we understand HTML. To visualise these components, Esko suggests so as to add a data-test-icon attribute that provides some textual content for use instead of the component when visualizing it for testing. With this,
<enter worth="foo" data-test-icon="[foo]" />
the enter component is visualized as [foo], with the sq. brackets hinting that the phrase “foo” sits inside an editable textual content field. Now if we add test-icons to our HTML template,
Go — Java is comparable
<ul class="todo-list">
vary .mannequin.AllItems
<li class=" if .IsCompleted accomplished finish ">
<div class="view">
<enter data-hx-post="/toggle/ .Id "
data-hx-target="part.todoapp"
data-hx-swap="outerHTML"
id="checkbox- .Id "
class="toggle"
sort="checkbox"
data-test-icon=" if .IsCompleted ✅ else ⬜ finish ">
<label for="checkbox- .Id "> .Title </label>
<button class="destroy" data-test-icon="❌️"></button>
</div>
</li>
{ finish }
</ul>
we are able to assert in opposition to its canonical visible illustration like this:
Go
func Test_visualize_html_example(t *testing.T)
mannequin := todo.NewList().
Add("One").
Add("Two").
AddCompleted("Three")
buf := renderTemplate("todo-list.tmpl", mannequin, "/")
anticipated := `
⬜ One ❌️
⬜ Two ❌️
✅ Three ❌️
`
assert.Equal(t, normalizeWhitespace(anticipated), visualizeHtml(buf.String()))
Java
@Take a look at
void visualize_html_example()
var mannequin = new TodoList()
.add("One")
.add("Two")
.addCompleted("Three");
var html = renderTemplate("/todo-list.tmpl", mannequin, "/");
assertThat(visualizeHtml(html))
.isEqualTo(normalizeWhitespace("""
⬜ One ❌️
⬜ Two ❌️
✅ Three ❌️
"""));
Right here is Esko Luontola’s Java implementation of the 2 features that make this attainable, and my translation to Go of his code.
Go
func visualizeHtml(html string) string huge
func normalizeWhitespace(s string) string
return strings.TrimSpace(replaceAll(s, "s+", " "))
func replaceAll(src, regex, repl string) string
re := regexp.MustCompile(regex)
return re.ReplaceAllString(src, repl)
supply
Java
public static String visualizeHtml(String html) sturdy
public static String normalizeWhitespace(String s)
return s.replaceAll("s+", " ").trim();
supply
On this part, we now have seen a way for asserting HTML content material that’s a substitute for the CSS selector-based approach utilized in the remainder of the article. Esko Luontola has reported nice success with it, and I hope readers have success with it too!
This method of asserting in opposition to giant, sophisticated knowledge constructions corresponding to HTML pages by lowering them to a canonical string model has no identify that I do know of. Martin Fowler urged “stringly asserted”, and from his suggestion comes the identify of this part.
