ConcurrentHashSet — implement equals and hashCode

platform/util/src/com/intellij/util/containers/ConcurrentHashSet.java

@@ -117,5 +117,41 @@ public class ConcurrentHashSet<K> implements Set<K> {
   public String toString() {
     return map.keySet().toString();
   }
+
+  @SuppressWarnings("deprecation")
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) {
+      return true;
+    }
+
+    if (obj instanceof ConcurrentHashSet) {
+      return map.equals(((ConcurrentHashSet)obj).map);
+    }
+
+    if (!(obj instanceof Set)) {
+      return false;
+    }
+
+    Set<?> c = (Set<?>)obj;
+    if (c.size() != size()) {
+      return false;
+    }
+
+    try {
+      return containsAll(c);
+    }
+    catch (ClassCastException ignored) {
+      return false;
+    }
+    catch (NullPointerException ignored) {
+      return false;
+    }
+  }
+
+  @Override
+  public int hashCode() {
+    return map.hashCode();
+  }
 }
 

platform/util/testSrc/com/intellij/util/containers/hash/ConcurrentHashSetTest.kt

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2000-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.util.containers.hash
+
+import com.intellij.util.containers.ConcurrentHashSet
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.Test
+
+class ConcurrentHashSetTest {
+  @Suppress("DEPRECATION")
+  @Test
+  fun testEquals() {
+    val set = ConcurrentHashSet<String>()
+    assertThat(set).isNotEqualTo(emptyMap<String, String>())
+    assertThat(set).isEqualTo(emptySet<String>())
+    assertThat(set).isEqualTo(ConcurrentHashSet<String>())
+
+    set.add("foo")
+    assertThat(set).isNotEqualTo(emptySet<String>())
+    assertThat(set).isEqualTo(setOf("foo"))
+    assertThat(set).isNotEqualTo(setOf("bar"))
+
+    val otherSet = ConcurrentHashSet<String>()
+    otherSet.add("bar")
+    assertThat(set).isNotEqualTo(otherSet)
+
+    otherSet.remove("bar")
+    otherSet.add("foo")
+    assertThat(set).isEqualTo(otherSet)
+  }
+}