Add DarcyWebMatchers with HasClass matcher

src/main/java/com/redhat/darcy/web/matchers/DarcyWebMatchers.java

@@ -0,0 +1,12 @@
+package com.redhat.darcy.web.matchers;
+
+import com.redhat.darcy.ui.matchers.DarcyMatchers;
+import com.redhat.darcy.web.api.elements.HtmlElement;
+
+import org.hamcrest.Matcher;
+
+public abstract class DarcyWebMatchers extends DarcyMatchers {
+    public static <T extends HtmlElement> Matcher<T> hasClass(Matcher<? super String> matcher) {
+        return new HasClass<>(matcher);
+    }
+}

src/main/java/com/redhat/darcy/web/matchers/HasClass.java

@@ -0,0 +1,35 @@
+package com.redhat.darcy.web.matchers;
+
+import com.redhat.darcy.web.api.elements.HtmlElement;
+
+import org.hamcrest.Description;
+import org.hamcrest.Matcher;
+import org.hamcrest.TypeSafeDiagnosingMatcher;
+
+public class HasClass<T extends HtmlElement> extends TypeSafeDiagnosingMatcher<T> {
+    private Matcher<? super String> matcher;
+
+    public HasClass(Matcher<? super String> matcher) {
+        this.matcher = matcher;
+    }
+
+    @Override
+    public void describeTo(Description description) {
+        description.appendText("an element that has the class ");
+        matcher.describeTo(description);
+    }
+
+    @Override
+    protected boolean matchesSafely(T t, Description description) {
+        for (String clazz : t.getClasses()) {
+            if (matcher.matches(clazz)) {
+                return true;
+            }
+        }
+
+        description.appendText("could not find a matching class in ")
+                .appendValue(t.getClasses());
+
+        return false;
+    }
+}

src/test/java/com/redhat/darcy/web/matchers/HasClassTest.java

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+package com.redhat.darcy.web.matchers;
+
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import com.redhat.darcy.web.api.elements.HtmlElement;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+import java.util.ArrayList;
+import java.util.List;
+
+@RunWith(JUnit4.class)
+public class HasClassTest {
+    @Test
+    public void shouldMatchFullClass() {
+        HasClass<HtmlElement> matcher = new HasClass<>(equalTo("clazz"));
+        HtmlElement mockElement = mock(HtmlElement.class);
+
+        List<String> classes = new ArrayList<>();
+        classes.add("clazz");
+        when(mockElement.getClasses()).thenReturn(classes);
+
+        assertTrue(matcher.matches(mockElement));
+    }
+
+    @Test
+    public void shouldMatchPartialClass() {
+        HasClass<HtmlElement> matcher = new HasClass<>(containsString("cla"));
+        HtmlElement mockElement = mock(HtmlElement.class);
+
+        List<String> classes = new ArrayList<>();
+        classes.add("clazz");
+        when(mockElement.getClasses()).thenReturn(classes);
+
+        assertTrue(matcher.matches(mockElement));
+    }
+
+    @Test
+    public void shouldNotMatchMissingClass() {
+        HasClass<HtmlElement> matcher = new HasClass<>(containsString("missing"));
+        HtmlElement mockElement = mock(HtmlElement.class);
+
+        List<String> classes = new ArrayList<>();
+        classes.add("clazz");
+        when(mockElement.getClasses()).thenReturn(classes);
+
+        assertFalse(matcher.matches(mockElement));
+    }
+}