Use Guava testlib for collection tests

gson/src/test/java/com/google/gson/JsonArrayAsListSuiteTest.java

@@ -0,0 +1,68 @@
+package com.google.gson;
+
+import com.google.common.collect.testing.ListTestSuiteBuilder;
+import com.google.common.collect.testing.SampleElements;
+import com.google.common.collect.testing.TestListGenerator;
+import com.google.common.collect.testing.features.CollectionFeature;
+import com.google.common.collect.testing.features.CollectionSize;
+import com.google.common.collect.testing.features.ListFeature;
+import java.util.List;
+import junit.framework.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.AllTests;
+
+/**
+ * Dynamic {@link ListTestSuiteBuilder List test suite} for {@link JsonArray#asList()}. This
+ * complements {@link JsonArrayAsListTest}, which can cover some cases which are not covered here,
+ * e.g. making sure changes in the {@code List} view are visible in the {@code JsonArray}.
+ */
+@RunWith(AllTests.class)
+public class JsonArrayAsListSuiteTest {
+  private static class ListGenerator implements TestListGenerator<JsonElement> {
+    @Override
+    public SampleElements<JsonElement> samples() {
+      return new SampleElements<JsonElement>(
+          JsonNull.INSTANCE,
+          new JsonPrimitive(true),
+          new JsonPrimitive("test"),
+          new JsonArray(),
+          new JsonObject());
+    }
+
+    @Override
+    public JsonElement[] createArray(int length) {
+      return new JsonElement[length];
+    }
+
+    @Override
+    public Iterable<JsonElement> order(List<JsonElement> insertionOrder) {
+      return insertionOrder;
+    }
+
+    @Override
+    public List<JsonElement> create(Object... elements) {
+      JsonArray array = new JsonArray();
+      for (Object element : elements) {
+        array.add((JsonElement) element);
+      }
+      return array.asList();
+    }
+  }
+
+  // Special method recognized by JUnit's `AllTests` runner
+  public static Test suite() {
+    return ListTestSuiteBuilder.using(new ListGenerator())
+        .withFeatures(
+            CollectionSize.ANY,
+            // Note: There is current a Guava bug which causes 'null additions' to not be tested if
+            // 'null queries' is enabled, see https://github.com/google/guava/issues/7401
+            CollectionFeature.ALLOWS_NULL_QUERIES,
+            CollectionFeature.RESTRICTS_ELEMENTS, // List only allows JsonElement
+            CollectionFeature.SUPPORTS_ADD,
+            ListFeature.REMOVE_OPERATIONS,
+            ListFeature.SUPPORTS_ADD_WITH_INDEX,
+            ListFeature.SUPPORTS_SET)
+        .named("JsonArray#asList")
+        .createTestSuite();
+  }
+}

gson/src/test/java/com/google/gson/JsonObjectAsMapSuiteTest.java

@@ -0,0 +1,86 @@
+package com.google.gson;
+
+import com.google.common.collect.testing.MapTestSuiteBuilder;
+import com.google.common.collect.testing.SampleElements;
+import com.google.common.collect.testing.TestMapGenerator;
+import com.google.common.collect.testing.features.CollectionFeature;
+import com.google.common.collect.testing.features.CollectionSize;
+import com.google.common.collect.testing.features.MapFeature;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import junit.framework.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.AllTests;
+
+/**
+ * Dynamic {@link MapTestSuiteBuilder Map test suite} for {@link JsonObject#asMap()}. This
+ * complements {@link JsonObjectAsMapTest}, which can cover some cases which are not covered here,
+ * e.g. making sure changes in the {@code Map} view are visible in the {@code JsonObject}.
+ */
+@RunWith(AllTests.class)
+public class JsonObjectAsMapSuiteTest {
+  private static class MapGenerator implements TestMapGenerator<String, JsonElement> {
+    @Override
+    public SampleElements<Entry<String, JsonElement>> samples() {
+      return new SampleElements<>(
+          Map.entry("one", JsonNull.INSTANCE),
+          Map.entry("two", new JsonPrimitive(true)),
+          Map.entry("three", new JsonPrimitive("test")),
+          Map.entry("four", new JsonArray()),
+          Map.entry("five", new JsonObject()));
+    }
+
+    @Override
+    public Map<String, JsonElement> create(Object... elements) {
+      JsonObject object = new JsonObject();
+      for (Object element : elements) {
+        var entry = (Entry<?, ?>) element;
+        object.add((String) entry.getKey(), (JsonElement) entry.getValue());
+      }
+      return object.asMap();
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public Entry<String, JsonElement>[] createArray(int length) {
+      return (Entry<String, JsonElement>[]) new Entry<?, ?>[length];
+    }
+
+    @Override
+    public Iterable<Entry<String, JsonElement>> order(
+        List<Entry<String, JsonElement>> insertionOrder) {
+      // Preserves insertion order
+      return insertionOrder;
+    }
+
+    @Override
+    public String[] createKeyArray(int length) {
+      return new String[length];
+    }
+
+    @Override
+    public JsonElement[] createValueArray(int length) {
+      return new JsonElement[length];
+    }
+  }
+
+  // Special method recognized by JUnit's `AllTests` runner
+  public static Test suite() {
+    return MapTestSuiteBuilder.using(new MapGenerator())
+        .withFeatures(
+            CollectionSize.ANY,
+            // Note: There is current a Guava bug which causes 'null additions' to not be tested if
+            // 'null queries' is enabled, see https://github.com/google/guava/issues/7401
+            MapFeature.ALLOWS_ANY_NULL_QUERIES,
+            MapFeature.RESTRICTS_KEYS, // Map only allows String keys
+            MapFeature.RESTRICTS_VALUES, // Map only allows JsonElement values
+            MapFeature.SUPPORTS_PUT,
+            MapFeature.SUPPORTS_REMOVE,
+            // Affects keySet, values and entrySet (?)
+            CollectionFeature.KNOWN_ORDER, // Map preserves insertion order
+            CollectionFeature.SUPPORTS_ITERATOR_REMOVE)
+        .named("JsonObject#asMap")
+        .createTestSuite();
+  }
+}

gson/src/test/java/com/google/gson/internal/LinkedTreeMapSuiteTest.java

@@ -0,0 +1,83 @@
+package com.google.gson.internal;
+
+import com.google.common.collect.testing.MapTestSuiteBuilder;
+import com.google.common.collect.testing.TestStringMapGenerator;
+import com.google.common.collect.testing.features.CollectionFeature;
+import com.google.common.collect.testing.features.CollectionSize;
+import com.google.common.collect.testing.features.Feature;
+import com.google.common.collect.testing.features.MapFeature;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import junit.framework.Test;
+import junit.framework.TestSuite;
+import org.junit.runner.RunWith;
+import org.junit.runners.AllTests;
+
+/**
+ * Dynamic {@link MapTestSuiteBuilder Map test suite} for {@link LinkedTreeMap}. This complements
+ * {@link LinkedTreeMapTest}.
+ */
+@RunWith(AllTests.class)
+public class LinkedTreeMapSuiteTest {
+  private static class MapGenerator extends TestStringMapGenerator {
+    private final boolean allowNullValues;
+
+    public MapGenerator(boolean allowNullValues) {
+      this.allowNullValues = allowNullValues;
+    }
+
+    @Override
+    protected Map<String, String> create(Entry<String, String>[] entries) {
+      var map = new LinkedTreeMap<String, String>(allowNullValues);
+      for (var entry : entries) {
+        map.put(entry.getKey(), entry.getValue());
+      }
+      return map;
+    }
+  }
+
+  private static Feature<?>[] createFeatures(Feature<?>... additionalFeatures) {
+    // Don't specify CollectionFeature.SERIALIZABLE because Guava testlib seems to assume
+    // deserialized Map has same properties as original map (e.g. disallowing null keys), but this
+    // is not the case for LinkedTreeMap which is serialized as JDK LinkedHashMap
+    var features =
+        new ArrayList<Feature<?>>(
+            List.of(
+                CollectionSize.ANY,
+                // Note: There is current a Guava bug which causes 'null additions' to not be tested
+                // if 'null queries' is enabled, see https://github.com/google/guava/issues/7401
+                MapFeature.ALLOWS_ANY_NULL_QUERIES,
+                MapFeature.RESTRICTS_KEYS, // Map only allows comparable keys
+                MapFeature.SUPPORTS_PUT,
+                MapFeature.SUPPORTS_REMOVE,
+                // Affects keySet, values and entrySet (?)
+                CollectionFeature.KNOWN_ORDER, // Map preserves insertion order
+                CollectionFeature.SUPPORTS_ITERATOR_REMOVE));
+    features.addAll(Arrays.asList(additionalFeatures));
+    return features.toArray(Feature[]::new);
+  }
+
+  // Special method recognized by JUnit's `AllTests` runner
+  public static Test suite() {
+    var nullValuesSuite =
+        MapTestSuiteBuilder.using(new MapGenerator(true))
+            .withFeatures(createFeatures(MapFeature.ALLOWS_NULL_VALUES))
+            .named("nullValues=true")
+            .createTestSuite();
+
+    var nonNullValuesSuite =
+        MapTestSuiteBuilder.using(new MapGenerator(false))
+            .withFeatures(createFeatures())
+            .named("nullValues=false")
+            .createTestSuite();
+
+    TestSuite testSuite = new TestSuite("LinkedTreeMap");
+    testSuite.addTest(nullValuesSuite);
+    testSuite.addTest(nonNullValuesSuite);
+
+    return testSuite;
+  }
+}