Simplify OutputGroupProviderTest.

Avoids constructing and manipulating expected value sets
for containsExactlyElementsIn when containsExactly will do.

--
MOS_MIGRATED_REVID=125371446
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/OutputGroupProviderTest.java b/src/test/java/com/google/devtools/build/lib/analysis/OutputGroupProviderTest.java
index c56f0dd..a6857b7 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/OutputGroupProviderTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/OutputGroupProviderTest.java
@@ -24,7 +24,6 @@
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
 
-import java.util.HashSet;
 import java.util.Set;
 
 /**
@@ -43,18 +42,13 @@
   @Test
   public void testDetermineOutputGroupsAddsToDefaults() throws Exception {
     Set<String> outputGroups = determineOutputGroups(ImmutableSet.of("x", "y", "z"), asList("+a"));
-    Set<String> expected = new HashSet<>(ImmutableSet.of("x", "y", "z"));
-    expected.add("a");
-    assertThat(outputGroups).containsExactlyElementsIn(expected);
+    assertThat(outputGroups).containsExactly("x", "y", "z", "a");
   }
 
   @Test
   public void testDetermineOutputGroupsRemovesFromDefaults() throws Exception {
     Set<String> outputGroups = determineOutputGroups(ImmutableSet.of("x", "y", "z"), asList("-y"));
-
-    Set<String> expected = new HashSet<>(ImmutableSet.of("x", "y", "z"));
-    expected.remove("y");
-    assertThat(outputGroups).containsExactlyElementsIn(expected);
+    assertThat(outputGroups).containsExactly("x", "z");
   }
 
   @Test
@@ -70,19 +64,17 @@
     Set<String> outputGroups =
         determineOutputGroups(ImmutableSet.of("x", "y", "z"), asList("-foo"));
     // "foo" doesn't exist, but that shouldn't be a problem.
-    assertThat(outputGroups).containsExactlyElementsIn(ImmutableSet.of("x", "y", "z"));
+    assertThat(outputGroups).containsExactly("x", "y", "z");
   }
 
   @Test
   public void testDetermineOutputGroupsRemovesPreviouslyAddedGroup() throws Exception {
     Set<String> outputGroups;
     outputGroups = determineOutputGroups(ImmutableSet.of("x", "y", "z"), asList("+a", "-a"));
-    assertThat(outputGroups).containsExactlyElementsIn(ImmutableSet.of("x", "y", "z"));
+    assertThat(outputGroups).containsExactly("x", "y", "z");
 
     // Order matters here.
     outputGroups = determineOutputGroups(ImmutableSet.of("x", "y", "z"), asList("-a", "+a"));
-    Set<String> expected = new HashSet<>(ImmutableSet.of("x", "y", "z"));
-    expected.add("a");
-    assertThat(outputGroups).containsExactlyElementsIn(expected);
+    assertThat(outputGroups).containsExactly("x", "y", "z", "a");
   }
 }