Improve error message for MultimapSubject.containsEntry()

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=127233406

core/src/main/java/com/google/common/truth/MultimapSubject.java

@@ -29,13 +29,13 @@
 import com.google.common.collect.SetMultimap;
 import com.google.common.collect.Sets;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
-
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.LinkedHashSet;
 import java.util.List;
-
+import java.util.Map.Entry;
+import java.util.Set;
 import javax.annotation.Nullable;
 
 /**
@@ -98,7 +98,27 @@ public void doesNotContainKey(@Nullable Object key) {
 
  /** Fails if the multimap does not contain the given entry. */
  public void containsEntry(@Nullable Object key, @Nullable Object value) {
+ // TODO(kak): Can we share any of this logic w/ MapSubject.containsEntry()?
  if (!getSubject().containsEntry(key, value)) {
+ Entry<Object, Object> entry = Maps.immutableEntry(key, value);
+ if (getSubject().containsKey(key)) {
+ failWithRawMessage(
+ "Not true that %s contains entry <%s>. However, it has a mapping from <%s> to <%s>",
+ getDisplaySubject(), entry, key, ((Multimap<Object, Object>) getSubject()).get(key));
+ }
+ if (getSubject().containsValue(value)) {
+ Set<Object> keys = new LinkedHashSet<Object>();
+ for (Entry<Object, Object> actualEntry :
+ ((Multimap<Object, Object>) getSubject()).entries()) {
+ if (Objects.equal(actualEntry.getValue(), value)) {
+ keys.add(actualEntry.getKey());
+ }
+ }
+ failWithRawMessage(
+ "Not true that %s contains entry <%s>. "
+ + "However, the following keys are mapped to <%s>: %s",
+ getDisplaySubject(), entry, value, keys);
+ }
  fail("contains entry", Maps.immutableEntry(key, value));
  }
  }

core/src/test/java/com/google/common/truth/MultimapSubjectTest.java

@@ -18,14 +18,14 @@
 import static com.google.common.truth.Truth.assertThat;
 import static org.junit.Assert.fail;
 
+import com.google.common.collect.ArrayListMultimap;
 import com.google.common.collect.HashMultimap;
 import com.google.common.collect.ImmutableListMultimap;
 import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.ImmutableSetMultimap;
 import com.google.common.collect.LinkedListMultimap;
 import com.google.common.collect.ListMultimap;
 import com.google.common.collect.Multimap;
-
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -283,6 +283,56 @@ public void containsEntryFailure() {
  }
  }
 
+ @Test
+ public void containsEntryWithNullValueNullExpected() {
+ ListMultimap<String, String> actual = ArrayListMultimap.create();
+ actual.put("a", null);
+ assertThat(actual).containsEntry("a", null);
+ }
+
+ @Test
+ public void failContainsEntry() {
+ ImmutableMultimap<String, String> actual = ImmutableMultimap.of("a", "A");
+ try {
+ assertThat(actual).containsEntry("a", "a");
+ fail("Should have thrown.");
+ } catch (AssertionError e) {
+ assertThat(e)
+ .hasMessage(
+ "Not true that <{a=[A]}> contains entry <a=a>. "
+ + "However, it has a mapping from <a> to <[A]>");
+ }
+ }
+
+ @Test
+ public void failContainsEntryWithNullValuePresentExpected() {
+ ListMultimap<String, String> actual = ArrayListMultimap.create();
+ actual.put("a", null);
+ try {
+ assertThat(actual).containsEntry("a", "A");
+ fail("Should have thrown.");
+ } catch (AssertionError e) {
+ assertThat(e)
+ .hasMessage(
+ "Not true that <{a=[null]}> contains entry <a=A>. "
+ + "However, it has a mapping from <a> to <[null]>");
+ }
+ }
+
+ @Test
+ public void failContainsEntryWithPresentValueNullExpected() {
+ ImmutableMultimap<String, String> actual = ImmutableMultimap.of("a", "A");
+ try {
+ assertThat(actual).containsEntry("a", null);
+ fail("Should have thrown.");
+ } catch (AssertionError e) {
+ assertThat(e)
+ .hasMessage(
+ "Not true that <{a=[A]}> contains entry <a=null>. "
+ + "However, it has a mapping from <a> to <[A]>");
+ }
+ }
+
  @Test
  public void doesNotContainEntry() {
  ImmutableMultimap<String, String> multimap = ImmutableMultimap.of("kurt", "kluever");