Add gson handler and tests

Added JacksonHandler which provides jackson behavior in gson.
Also added classes to facilitate testing of gson serializations.
Added compareGson(xxx, Class).
Removed trailing spaces from some files.
Updated license dates.
Replaced incorrect constant with ${xxx} in json test file.
Fixed typo in test method name.

Change-Id: If05b654d76a4ffc88646f03334be82b32506f28f
Issue-ID: POLICY-1428
Signed-off-by: Jim Hahn <jrh3@att.com>

3 files changed, 388 insertions, 0 deletions

diff --git a/utils-test/src/test/java/org/onap/policy/common/utils/gson/GsonSerializerTest.java b/utils-test/src/test/java/org/onap/policy/common/utils/gson/GsonSerializerTest.java
new file mode 100644
index 00000000..82f5ede0
--- /dev/null
+++ b/utils-test/src/test/java/org/onap/policy/common/utils/gson/GsonSerializerTest.java
@@ -0,0 +1,47 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.gson;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.io.StringReader;
+import org.junit.Test;
+
+public class GsonSerializerTest {
+
+    @Test
+    public void testReadJsonReader() {
+        JsonReader rdr = new JsonReader(new StringReader("10"));
+
+        GsonSerializer<Object> ser = new GsonSerializer<Object>() {
+            @Override
+            public void write(JsonWriter out, Object value) throws IOException {
+                // do nothing
+            }
+        };
+
+        assertThatThrownBy(() -> ser.read(rdr)).isInstanceOf(UnsupportedOperationException.class)
+                        .hasMessage("read from pseudo TypeAdapter");
+    }
+}
diff --git a/utils-test/src/test/java/org/onap/policy/common/utils/gson/GsonTestUtilsBuilderTest.java b/utils-test/src/test/java/org/onap/policy/common/utils/gson/GsonTestUtilsBuilderTest.java
new file mode 100644
index 00000000..3e4244dd
--- /dev/null
+++ b/utils-test/src/test/java/org/onap/policy/common/utils/gson/GsonTestUtilsBuilderTest.java
@@ -0,0 +1,93 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.gson;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import org.junit.Before;
+import org.junit.Test;
+
+public class GsonTestUtilsBuilderTest {
+
+    private GsonTestUtilsBuilder bldr;
+    private GsonTestUtils utils;
+
+    @Before
+    public void setUp() {
+        bldr = new MyBuilder();
+        utils = bldr.build();
+    }
+
+    @Test
+    public void testBuilderAddMock() {
+        PreMock pre = mock(PreMock.class);
+        when(pre.getId()).thenReturn(2000);
+
+        assertEquals("{\"name\":2000}", utils.gsonEncode(pre));
+    }
+
+    /**
+     * Builder that provides an adapter for mock(PreMock.class).
+     */
+    private static class MyBuilder extends GsonTestUtilsBuilder {
+        public MyBuilder() {
+            TypeAdapterFactory sgson = new TypeAdapterFactory() {
+                @Override
+                public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
+                    Class<? super T> clazz = type.getRawType();
+
+                    if (PreMock.class.isAssignableFrom(clazz)) {
+                        return new GsonSerializer<T>() {
+                            @Override
+                            public void write(JsonWriter out, T value) throws IOException {
+                                PreMock obj = (PreMock) value;
+                                out.beginObject().name("name").value(obj.getId()).endObject();
+                            }
+                        };
+                    }
+
+                    return null;
+                }
+            };
+
+            addMock(PreMock.class, sgson);
+        }
+    }
+
+    /**
+     * Class that will be mocked.
+     */
+    public static class PreMock {
+        protected int id = 1000;
+
+        public int getId() {
+            return id;
+        }
+    }
+}
diff --git a/utils-test/src/test/java/org/onap/policy/common/utils/gson/GsonTestUtilsTest.java b/utils-test/src/test/java/org/onap/policy/common/utils/gson/GsonTestUtilsTest.java
new file mode 100644
index 00000000..39cde7dc
--- /dev/null
+++ b/utils-test/src/test/java/org/onap/policy/common/utils/gson/GsonTestUtilsTest.java
@@ -0,0 +1,248 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.utils.gson;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonNull;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParseException;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import javax.script.ScriptException;
+import org.junit.Before;
+import org.junit.Test;
+
+public class GsonTestUtilsTest {
+    private static final String HELLO = "hello";
+
+    private GsonTestUtils utils;
+
+    @Before
+    public void setUp() {
+        utils = new GsonTestUtils();
+    }
+
+    @Test
+    public void testGetGson() {
+        assertNotNull(utils.getGson());
+    }
+
+    @Test
+    public void testGsonRoundTrip() {
+        Data data = new Data();
+        data.setId(500);
+
+        // try with null text
+        data.setText(null);
+        assertEquals(data.toString(), utils.gsonRoundTrip(data, Data.class).toString());
+
+        // try with non-null text
+        data.setText(HELLO);
+        assertEquals(data.toString(), utils.gsonRoundTrip(data, Data.class).toString());
+    }
+
+    @Test
+    public void testCompareGsonObjectClass_testCompareGsonObjectFile() {
+        Data data = new Data();
+        data.setId(500);
+        data.setText(HELLO);
+
+        utils.compareGson(data, GsonTestUtilsTest.class);
+
+        // file not found
+        assertThatThrownBy(() -> utils.compareGson(data,
+                        new File(GsonTestUtilsTest.class.getSimpleName() + "-NotFound.json")))
+                                        .isInstanceOf(JsonParseException.class)
+                                        .hasCauseInstanceOf(FileNotFoundException.class);
+
+        // force I/O error while reading file
+        GsonTestUtils utils2 = new GsonTestUtils() {
+            @Override
+            protected String readFile(File file) throws IOException {
+                throw new IOException("expected exception");
+            }
+        };
+        assertThatThrownBy(() -> utils2.compareGson(data, GsonTestUtilsTest.class))
+                        .isInstanceOf(JsonParseException.class).hasCauseInstanceOf(IOException.class)
+                        .hasMessage("error reading: GsonTestUtilsTest.json");
+    }
+
+    @Test
+    public void testCompareGsonObjectString() {
+        Data data = new Data();
+        data.setId(600);
+        data.setText(HELLO);
+
+        utils.compareGson(data, "{'id': ${obj.id}, 'text': '${obj.text}'}".replace('\'', '"'));
+    }
+
+    @Test
+    public void testCompareGsonObjectJsonElement() {
+        Data data = new Data();
+        data.setId(650);
+        data.setText(HELLO);
+
+        JsonObject json = new JsonObject();
+        json.addProperty("id", data.getId());
+        json.addProperty("text", data.getText());
+
+        utils.compareGson(data, json);
+
+        // mismatch
+        data.setText("world");
+        assertThatThrownBy(() -> utils.compareGson(data, json)).isInstanceOf(AssertionError.class);
+    }
+
+    @Test
+    public void testApplyScripts() {
+        Data data = new Data();
+        data.setId(700);
+        data.setText(HELLO);
+
+        String result = utils.applyScripts("no interpolation", data);
+        assertEquals("no interpolation", result);
+
+        result = utils.applyScripts("${obj.id} at start, ${obj.text} in middle, and end ${obj.id}", data);
+        assertEquals("700 at start, hello in middle, and end 700", result);
+
+        // try null value
+        data.setText(null);
+        result = utils.applyScripts("use ${obj.text} this", data);
+        assertEquals("use null this", result);
+
+        assertThatThrownBy(() -> utils.applyScripts("use ${obj.text} this", null)).isInstanceOf(RuntimeException.class)
+                        .hasCauseInstanceOf(ScriptException.class).hasMessage("cannot expand element: ${obj.text}");
+    }
+
+    @Test
+    public void testReorderJsonObject() {
+        // insert properties in a non-alphabetical order
+        JsonObject inner = new JsonObject();
+        inner.addProperty("objBint", 100);
+        inner.add("objBNull", JsonNull.INSTANCE);
+        inner.addProperty("objB", true);
+
+        JsonArray arr = new JsonArray();
+        arr.add(110);
+        arr.add(inner);
+        arr.add(false);
+
+        JsonObject outer = new JsonObject();
+        outer.add("objANull", JsonNull.INSTANCE);
+        outer.addProperty("objA", true);
+        outer.addProperty("objAStr", "obj-a-string");
+        outer.add("nested-array", arr);
+
+        outer = utils.reorder(outer);
+        assertEquals("{'nested-array':[110,{'objB':true,'objBint':100},false],'objA':true,'objAStr':'obj-a-string'}"
+                        .replace('\'', '"'), outer.toString());
+    }
+
+    @Test
+    public void testReorderJsonArray() {
+        // insert properties in a non-alphabetical order
+        JsonObject inner = new JsonObject();
+        inner.add("objCNull", JsonNull.INSTANCE);
+        inner.addProperty("objCStr", "obj-c-string");
+        inner.addProperty("objC", true);
+
+        JsonArray arr = new JsonArray();
+        arr.add(200);
+        arr.add(inner);
+        arr.add(false);
+
+        arr = utils.reorder(arr);
+        assertEquals("[200,{'objC':true,'objCStr':'obj-c-string'},false]".replace('\'', '"'), arr.toString());
+    }
+
+    @Test
+    public void testReorderJsonElement() {
+        // null element
+        JsonElement jsonEl = null;
+        assertNull(utils.reorder(jsonEl));
+
+        // object element
+        JsonObject obj = new JsonObject();
+        obj.add("objDNull", JsonNull.INSTANCE);
+        obj.addProperty("objDStr", "obj-d-string");
+        obj.addProperty("objD", true);
+        jsonEl = obj;
+        jsonEl = utils.reorder(jsonEl);
+        assertEquals("{'objD':true,'objDStr':'obj-d-string'}".replace('\'', '"'), jsonEl.toString());
+
+        // boolean
+        jsonEl = obj.get("objD");
+        jsonEl = utils.reorder(jsonEl);
+        assertEquals("true", jsonEl.toString());
+
+        // JsonNull
+        jsonEl = JsonNull.INSTANCE;
+        jsonEl = utils.reorder(jsonEl);
+        assertEquals("null", jsonEl.toString());
+
+        // array element
+        JsonObject inner = new JsonObject();
+        inner.add("objENull", JsonNull.INSTANCE);
+        inner.addProperty("objEStr", "obj-e-string");
+        inner.addProperty("objE", true);
+
+        JsonArray arr = new JsonArray();
+        arr.add(300);
+        arr.add(inner);
+        arr.add(false);
+        jsonEl = arr;
+        jsonEl = utils.reorder(jsonEl);
+        assertEquals("[300,{'objE':true,'objEStr':'obj-e-string'},false]".replace('\'', '"'), jsonEl.toString());
+    }
+
+    public static class Data {
+        private int id;
+        private String text;
+
+        public int getId() {
+            return id;
+        }
+
+        public void setId(int id) {
+            this.id = id;
+        }
+
+        public String getText() {
+            return text;
+        }
+
+        public void setText(String text) {
+            this.text = text;
+        }
+
+        @Override
+        public String toString() {
+            return "Data [id=" + id + ", text=" + text + "]";
+        }
+    }
+}