Optional matchers (hamcrest#421)

hamcrest/src/main/java/org/hamcrest/Matchers.java

@@ -3,8 +3,11 @@
 import org.hamcrest.collection.ArrayMatching;
 import org.hamcrest.core.IsIterableContaining;
 import org.hamcrest.core.StringRegularExpression;
+import org.hamcrest.optional.OptionalEmpty;
+import org.hamcrest.optional.OptionalWithValue;
 import org.hamcrest.text.IsEqualCompressingWhiteSpace;
 
+import java.util.Optional;
 import java.util.regex.Pattern;
 
 /**
@@ -2184,4 +2187,45 @@ public static org.hamcrest.Matcher<org.w3c.dom.Node> hasXPath(java.lang.String x
     return org.hamcrest.xml.HasXPath.hasXPath(xPath, namespaceContext);
   }
 
+  /**
+   * Matcher that expects empty {@link Optional}.
+   *
+   * @param <T> type of optional value
+   * @return The matcher.
+   */
+  public static <T> Matcher<Optional<T>> emptyOptional() {
+    return OptionalEmpty.emptyOptional();
+  }
+
+  /**
+   * Matcher for {@link Optional} that expects that value is present.
+   *
+   * @param <T> type of optional value
+   * @return The matcher.
+   */
+  public static <T> Matcher<Optional<T>> optionalWithValue() {
+    return OptionalWithValue.optionalWithValue();
+  }
+
+  /**
+   * Matcher for {@link Optional} that expects that value is present and is equal to <code>value</code>
+   *
+   * @param <T> type of optional value
+   * @param value to validate present optional value
+   * @return The matcher.
+   */
+  public static <T> Matcher<Optional<T>> optionalWithValue(T value) {
+    return OptionalWithValue.optionalWithValue(value);
+  }
+
+  /**
+   * Matcher for {@link Optional} that expects that value is present and matches <code>matcher</code>
+   *
+   * @param <T> type of optional value
+   * @param matcher matcher to validate present optional value
+   * @return The matcher.
+   */
+  public static <T> Matcher<Optional<T>> optionalWithValue(Matcher<? super T> matcher) {
+    return OptionalWithValue.optionalWithValue(matcher);
+  }
 }

hamcrest/src/main/java/org/hamcrest/optional/OptionalEmpty.java

@@ -0,0 +1,36 @@
+package org.hamcrest.optional;
+
+import org.hamcrest.Description;
+import org.hamcrest.Matcher;
+import org.hamcrest.TypeSafeDiagnosingMatcher;
+
+import java.util.Optional;
+
+/**
+ * Matcher that expects empty {@link Optional}.
+
+ * @param <T> type of {@link Optional} value
+ */
+public class OptionalEmpty<T> extends TypeSafeDiagnosingMatcher<Optional<T>> {
+
+    /**
+     * Matcher that expects empty {@link Optional}.
+     *
+     * @param <T> type of optional value
+     * @return The matcher.
+     */
+    public static <T> Matcher<Optional<T>> emptyOptional() {
+        return new OptionalEmpty<>();
+    }
+
+    @Override
+    protected boolean matchesSafely(Optional<T> value, Description mismatchDescription) {
+        mismatchDescription.appendText("is " + value);
+        return !value.isPresent();
+    }
+
+    @Override
+    public void describeTo(Description description) {
+        description.appendText("empty");
+    }
+}

hamcrest/src/main/java/org/hamcrest/optional/OptionalWithValue.java

@@ -0,0 +1,73 @@
+package org.hamcrest.optional;
+
+import org.hamcrest.Description;
+import org.hamcrest.Matcher;
+import org.hamcrest.TypeSafeDiagnosingMatcher;
+import org.hamcrest.core.IsAnything;
+
+import java.util.Optional;
+
+import static org.hamcrest.core.IsEqual.equalTo;
+
+/**
+ * Matcher for {@link Optional} that expects that value is present.
+ *
+ * @param <T> type of {@link Optional} value
+ */
+public class OptionalWithValue<T> extends TypeSafeDiagnosingMatcher<Optional<T>> {
+
+    private final Matcher<? super T> matcher;
+
+    /**
+     * Constructor.
+     *
+     * @param matcher matcher to validate present optional value
+     */
+    public OptionalWithValue(Matcher<? super T> matcher) {
+        this.matcher = matcher;
+    }
+
+    /**
+     * Matcher for {@link Optional} that expects that value is present.
+     *
+     * @param <T> type of optional value
+     * @return The matcher.
+     */
+    public static <T> Matcher<Optional<T>> optionalWithValue() {
+        return new OptionalWithValue<>(IsAnything.anything("any"));
+    }
+
+    /**
+     * Matcher for {@link Optional} that expects that value is present and is equal to <code>value</code>
+     *
+     * @param <T> type of optional value
+     * @param value to validate present optional value
+     * @return The matcher.
+     */
+    public static <T> Matcher<Optional<T>> optionalWithValue(T value) {
+        return new OptionalWithValue<>(equalTo(value));
+    }
+
+    /**
+     * Matcher for {@link Optional} that expects that value is present and matches <code>matcher</code>
+     *
+     * @param <T> type of optional value
+     * @param matcher matcher to validate present optional value
+     * @return The matcher.
+     */
+    public static <T> Matcher<Optional<T>> optionalWithValue(Matcher<? super T> matcher) {
+        return new OptionalWithValue<>(matcher);
+    }
+
+    @Override
+    protected boolean matchesSafely(Optional<T> value, Description mismatchDescription) {
+        mismatchDescription.appendText("is " + value);
+        return value.isPresent() && matcher.matches(value.get());
+    }
+
+    @Override
+    public void describeTo(Description description) {
+        description.appendText("present and matches ")
+                .appendDescriptionOf(matcher);
+    }
+}

hamcrest/src/test/java/org/hamcrest/optional/OptionalMatchersTest.java

@@ -0,0 +1,103 @@
+package org.hamcrest.optional;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.not;
+import static org.hamcrest.optional.OptionalEmpty.emptyOptional;
+import static org.hamcrest.optional.OptionalWithValue.optionalWithValue;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThrows;
+
+import java.util.Optional;
+
+import org.junit.Test;
+
+public class OptionalMatchersTest {
+
+    @Test
+    public void checkEmptyOptional() {
+        assertThat(Optional.empty(), is(emptyOptional()));
+        assertThat(Optional.of(1), not(emptyOptional()));
+    }
+
+    @Test
+    public void checkEmptyOptionalFailure() {
+        AssertionError failure = assertThrows(AssertionError.class, () -> {
+            assertThat(Optional.of(1), emptyOptional());
+        });
+        assertEquals("\n" +
+                "Expected: empty\n" +
+                "     but: is Optional[1]", failure.getMessage());
+    }
+
+    @Test
+    public void checkEmptyOptionalIsFailure() {
+        AssertionError failure = assertThrows(AssertionError.class, () -> {
+            assertThat(Optional.of(1), is(emptyOptional()));
+        });
+        assertEquals("\n" +
+                "Expected: is empty\n" +
+                "     but: is Optional[1]", failure.getMessage());
+    }
+
+    @Test
+    public void checkEmptyOptionalIsNotFailure() {
+        AssertionError failure = assertThrows(AssertionError.class, () -> {
+            assertThat(Optional.empty(), is(not(emptyOptional())));
+        });
+        assertEquals("\n" +
+                "Expected: is not empty\n" +
+                "     but: was <Optional.empty>", failure.getMessage());
+    }
+
+    @Test
+    public void checkWithValue() {
+        assertThat(Optional.empty(), not(optionalWithValue()));
+        assertThat(Optional.of(1), is(optionalWithValue()));
+    }
+
+    @Test
+    public void checkWithMatchingValue() {
+        assertThat(Optional.empty(), not(optionalWithValue(equalTo(1))));
+        assertThat(Optional.of(1), is(optionalWithValue(equalTo(1))));
+        assertThat(Optional.of(1), not(optionalWithValue(equalTo(1L))));
+    }
+
+    @Test
+    public void checkWithLiteralValue() {
+        assertThat(Optional.empty(), not(optionalWithValue(1)));
+        assertThat(Optional.of(1), is(optionalWithValue(1)));
+        assertThat(Optional.of(1), not(optionalWithValue(1L)));
+    }
+
+    @Test
+    public void checkWithValueFailure() {
+        AssertionError failure = assertThrows(AssertionError.class, () -> {
+            assertThat(Optional.empty(), is(optionalWithValue()));
+        });
+        assertEquals("\n" +
+                "Expected: is present and matches any\n" +
+                "     but: is Optional.empty", failure.getMessage());
+    }
+
+    @Test
+    public void checkWithMatchingValueFailure() {
+        AssertionError failure = assertThrows(AssertionError.class, () -> {
+            assertThat(Optional.empty(), is(optionalWithValue(equalTo(1))));
+        });
+        assertEquals("\n" +
+                "Expected: is present and matches <1>\n" +
+                "     but: is Optional.empty", failure.getMessage());
+    }
+
+    @Test
+    public void checkWithLiteralValueFailure() {
+        AssertionError failure = assertThrows(AssertionError.class, () -> {
+            assertThat(Optional.of("text"), is(optionalWithValue("Hello, world")));
+        });
+        assertEquals("\n" +
+                "Expected: is present and matches \"Hello, world\"\n" +
+                "     but: is Optional[text]", failure.getMessage());
+    }
+}