Add exact option to AssertLegacyTrait::assertLink(), WebAssert::linkExists() and WebAssert::linkNotExists()

I think we should use named_exact in our WebAssert because we really want to check that the link name is there standalone, not as part of some other link.

Yes, let's try to use named_exact for both and see where the fails are. From that issue I only see that tour tests were failing which are not converted yet anyway.

I looked into the test fails from #7 and the problem is for example that a link Manage fields <span class="visually-hidden">(active tab)</span> of course does not match with named_exact when only "Manage fields" is passed in.

That makes me think that our current behavior of linkExists() is correct. There might be other parts in a link label (icons, images, hidden spans for accessibility) that are not relevant for testing. So just using the "named" selector which does partial matches seems fine to me.

So we could just change the behavior of linkNotExists() to named_exact, but that also feels wrong. It really should work the same as linkExists() except of being reversed.

+++ b/core/tests/Drupal/Tests/WebAssert.php
@@ -221,13 +221,22 @@ public function titleEquals($expected_title) {
-  public function linkExists($label, $index = 0, $message = '') {
+  public function linkExists($label, $index = 0, $message = '', $exact = FALSE) {

I would make exact the default, its always better to be strict than less strict. If you don't need the strict behaviour then you'll see it in your test.
In other others explicit > implicit. I believe this is exactly what @klausi wrote before.

Making exact default will break existing tests (see #7). Are we ok with that ?

Mh, that's tricky, I guess we cannot risk that now.

Another idea I just had, have a method linkExistsExact to make it a bit easier to read. Any thoughts/opinions about that?

The dockblock says: "Passes if a link with the specified label is found." This implies the exact label.

+++ b/core/tests/Drupal/Tests/WebAssert.php
@@ -221,13 +221,22 @@ public function titleEquals($expected_title) {
+  public function linkExists($label, $index = 0, $message = '', $exact = FALSE) {

How about we reverse this? $exact should default to TRUE, since the expectation is that we're looking for the exact label.

Then for special-case failing legacy cases, we should add FALSE to the assertion with a todo/follow-up.

I like it "obviously". Do you mind adding some test coverage for those?

+++ b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
@@ -138,6 +138,58 @@ public function testPipeCharInLocator() {
+    try {
+      $this->assertSession()->linkExistsExact('foo|bar');
+      $this->fail('The exactly "foor|bar" label link was found.');
+    }
+    catch (ExpectationException $e) {
+      $this->pass('testLinkNonExistsExact correctly failed. The exactly "foor|bar" label link was not found.');
+    }
...
+    try {
+      $this->assertSession()->linkNotExistsExact('foo|bar|baz');
+      $this->fail('The exactly "foo|bar|baz" label link was not found.');
+    }
+    catch (ExpectationException $e) {
+      $this->pass('testNotLinkNonExistsExact correctly failed. The exactly "foo|bar|baz" label link was found.');

You can use setExpectedException here. Any reason why not?

+++ b/core/tests/Drupal/FunctionalTests/BrowserTestBaseTest.php
@@ -152,15 +152,10 @@ public function testLinkExistsExact() {
-    catch (ExpectationException $e) {
...
+    $this->setExpectedException('\Exception', 'Link with label foo|bar found');

@@ -178,15 +173,10 @@ public function testNotLinkExistsExact() {
-    catch (ExpectationException $e) {
...
+    $this->setExpectedException('\Exception', 'Link with label foo|bar|baz not found');

Note: You can specify which exception you expect. Let's do that as we did before :)

Specified expected exception.
Edited function names to match tested method.

Nice! I think this is good to go now

dded @dawehner to issue credits for numerous reviews.
Added @klausi for investigating test fails and providing reviews.

Committed as e562b4e and pushed to 8.4.x.

Unpostponed #2767275: Convert web tests to browser tests for tour module