Merge "Add gson handler and tests"

3 files changed, 412 insertions, 0 deletions

diff --git a/utils-test/src/main/java/org/onap/policy/common/utils/gson/GsonSerializer.java b/utils-test/src/main/java/org/onap/policy/common/utils/gson/GsonSerializer.java
new file mode 100644
index 00000000..db9c1c7e
--- /dev/null
+++ b/utils-test/src/main/java/org/onap/policy/common/utils/gson/GsonSerializer.java
@@ -0,0 +1,37 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * policy-management
+ * ================================================================================
+ * Copyright (C) 2017-2018 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 com.google.gson.TypeAdapter;
+import com.google.gson.stream.JsonReader;
+import java.io.IOException;
+
+/**
+ * Gson serializer, providing stub implementation of "read".
+ *
+ * @param <T> type of object that this serializes
+ */
+public abstract class GsonSerializer<T> extends TypeAdapter<T> {
+    @Override
+    public T read(JsonReader in) throws IOException {
+        throw new UnsupportedOperationException("read from pseudo TypeAdapter");
+    }
+}
diff --git a/utils-test/src/main/java/org/onap/policy/common/utils/gson/GsonTestUtils.java b/utils-test/src/main/java/org/onap/policy/common/utils/gson/GsonTestUtils.java
new file mode 100644
index 00000000..bfdca97c
--- /dev/null
+++ b/utils-test/src/main/java/org/onap/policy/common/utils/gson/GsonTestUtils.java
@@ -0,0 +1,314 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * policy-management
+ * ================================================================================
+ * Copyright (C) 2017-2018 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 com.google.gson.Gson;
+import com.google.gson.JsonArray;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParseException;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map.Entry;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import javax.script.Bindings;
+import javax.script.ScriptEngine;
+import javax.script.ScriptEngineManager;
+import javax.script.ScriptException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Utilities used to test encoding and decoding of Policy objects.
+ */
+public class GsonTestUtils {
+
+    private static final Logger logger = LoggerFactory.getLogger(GsonTestUtils.class);
+
+    /**
+     * Matches script items, of the form ${xxx}, within text.
+     */
+    private static final Pattern SCRIPT_PAT = Pattern.compile("\\$\\{([^}]+)\\}");
+
+    /**
+     * Engine used to interpolate strings before they're compared.
+     */
+    private static volatile ScriptEngine engine = null;
+
+    /**
+     * Used to encode and decode an object via gson.
+     */
+    private Gson gson;
+
+    /**
+     * Constructs the object.
+     */
+    public GsonTestUtils() {
+        GsonTestUtils other = new GsonTestUtilsBuilder().build();
+
+        gson = other.gson;
+    }
+
+    /**
+     * Constructs the object.
+     *
+     * @param gson used to encode via gson
+     */
+    protected GsonTestUtils(Gson gson) {
+        this.gson = gson;
+    }
+
+    public Gson getGson() {
+        return gson;
+    }
+
+    /**
+     * Serializes and then deserializes an object using gson.
+     *
+     * @param object the object to be serialized
+     * @param clazz the class of object to deserialize
+     * @return the deserialized object
+     */
+    public <T> T gsonRoundTrip(T object, Class<T> clazz) {
+        String sgson = gsonEncode(object);
+        return gson.fromJson(sgson, clazz);
+    }
+
+    /**
+     * Encodes an object using gson and then compares it to the expected value, after
+     * sorting the elements. The class name is used to find the json file, whose contents
+     * is interpolated (i.e., script elements, of the form ${obj.xxx}, are expanded).
+     *
+     * @param object the object to be encoded
+     * @param expected the expected value
+     * @throws Exception if the file cannot be read
+     */
+    public void compareGson(Object object, Class<?> expected) {
+        compareGson(object, new File(expected.getSimpleName() + ".json"));
+    }
+
+    /**
+     * Encodes an object using gson and then compares it to the expected value, after
+     * sorting the elements. The content of the file is interpolated (i.e., script
+     * elements, of the form ${obj.xxx}, are expanded).
+     *
+     * @param object the object to be encoded
+     * @param expected the expected value
+     * @throws Exception if the file cannot be read
+     */
+    public void compareGson(Object object, File expected) {
+        // file is not required to have a full path - find it via getResource()
+        URL url = object.getClass().getResource(expected.getName());
+        if (url == null) {
+            throw new JsonParseException(new FileNotFoundException(expected.getName()));
+        }
+
+        String expectedText;
+        try {
+            expectedText = readFile(new File(url.getFile()));
+
+        } catch (IOException e) {
+            throw new JsonParseException("error reading: " + expected, e);
+        }
+
+        compareGson(object, expectedText);
+    }
+
+    /**
+     * Encodes an object using gson and then compares it to the expected value, after
+     * sorting the elements. The expected value is interpolated (i.e., script elements, of
+     * the form ${obj.xxx}, are expanded).
+     *
+     * @param object the object to be encoded
+     * @param expected the expected value
+     */
+    public void compareGson(Object object, String expected) {
+        String result = applyScripts(expected, object);
+        compareGson(object, gson.fromJson(result, JsonElement.class));
+    }
+
+    /**
+     * Encodes an object using gson and then compares it to the expected value, after
+     * sorting the elements.
+     *
+     * @param object the object to be encoded
+     * @param expected the expected value
+     */
+    public void compareGson(Object object, JsonElement expected) {
+        String sgson = gsonEncode(object);
+
+        JsonElement gsonjo = reorder(gson.fromJson(sgson, JsonElement.class));
+        JsonElement expjo = reorder(expected);
+
+        assertEquals(expjo.toString(), gsonjo.toString());
+    }
+
+    /**
+     * Reads the content of a file.
+     * @param file file to read
+     * @return the content of the file
+     * @throws IOException if an error occurs
+     */
+    protected String readFile(File file) throws IOException {
+        return new String(Files.readAllBytes(file.toPath()), StandardCharsets.UTF_8);
+    }
+
+
+    /**
+     * Interpolates script elements, of the form ${obj.xxx}, within some text. The script
+     * is evaluated via javascript, where "obj" references the object used by each script
+     * element.
+     *
+     * @param object object to be used by the script
+     * @param text text to be evaluated
+     * @return the text, after interpolating the script elements
+     */
+    public String applyScripts(String text, Object object) {
+        Matcher mat = SCRIPT_PAT.matcher(text);
+        if (!mat.find()) {
+            // contains no script elements - just return it as is
+            return text;
+        }
+
+        // create the engine and bind the object to the variable, "obj"
+        if (engine == null) {
+            // race condition here, but it's ok to overwrite with a new engine
+            engine = new ScriptEngineManager().getEngineByName("javascript");
+        }
+
+        Bindings bindings = engine.createBindings();
+        bindings.put("obj", object);
+
+        // work our way through the text, interpolating script elements as we go
+        StringBuilder bldr = new StringBuilder();
+        int ilast = 0;
+        mat.reset();
+        while (mat.find(ilast)) {
+            // append segment that appears between last match and this
+            int inext = mat.start();
+            bldr.append(text.substring(ilast, inext));
+
+            // next match begins after the current match
+            ilast = mat.end();
+
+            // interpolate the script
+            String script = mat.group(1);
+            try {
+                Object result = engine.eval(script, bindings);
+                bldr.append(result == null ? "null" : result.toString());
+
+            } catch (ScriptException e) {
+                throw new RuntimeException("cannot expand element: " + mat.group(), e);
+            }
+        }
+
+        // append final segment
+        bldr.append(text.substring(ilast));
+
+        return bldr.toString();
+    }
+
+    /**
+     * Encodes an object using gson.
+     *
+     * @param object the object to be encoded
+     * @return the encoded object
+     */
+    public String gsonEncode(Object object) {
+        String sgson = gson.toJson(object);
+        logger.debug("gson=" + sgson);
+        return sgson;
+    }
+
+    /**
+     * Recursively re-orders a json object, arranging the keys alphabetically and removing
+     * null items.
+     *
+     * @param jsonObj object from which nulls are to be removed
+     * @return a new object, without the null items
+     */
+    public JsonObject reorder(JsonObject jsonObj) {
+        JsonObject newjo = new JsonObject();
+
+        // sort the keys before copying to the new object
+        List<Entry<String, JsonElement>> sortedSet = new ArrayList<>(jsonObj.entrySet());
+        Collections.sort(sortedSet, (left, right) -> left.getKey().compareTo(right.getKey()));
+
+        for (Entry<String, JsonElement> ent : sortedSet) {
+            JsonElement val = ent.getValue();
+            if (val.isJsonNull()) {
+                continue;
+            }
+
+            newjo.add(ent.getKey(), reorder(val));
+        }
+
+        return newjo;
+    }
+
+    /**
+     * Recursively re-orders a json array, arranging the keys alphabetically and removing
+     * null items.
+     *
+     * @param jsonArray array from which nulls are to be removed
+     * @return a new array, with null items removed from all elements
+     */
+    public JsonArray reorder(JsonArray jsonArray) {
+        JsonArray newarr = new JsonArray();
+        for (JsonElement ent : jsonArray) {
+            newarr.add(reorder(ent));
+        }
+
+        return newarr;
+    }
+
+    /**
+     * Recursively re-orders a json element, arranging the keys alphabetically and
+     * removing null items.
+     *
+     * @param jsonEl element from which nulls are to be removed
+     * @return a new element, with null items removed
+     */
+    public JsonElement reorder(JsonElement jsonEl) {
+        if (jsonEl == null) {
+            return null;
+
+        } else if (jsonEl.isJsonObject()) {
+            return reorder(jsonEl.getAsJsonObject());
+
+        } else if (jsonEl.isJsonArray()) {
+            return reorder(jsonEl.getAsJsonArray());
+
+        } else {
+            return jsonEl;
+        }
+    }
+}
diff --git a/utils-test/src/main/java/org/onap/policy/common/utils/gson/GsonTestUtilsBuilder.java b/utils-test/src/main/java/org/onap/policy/common/utils/gson/GsonTestUtilsBuilder.java
new file mode 100644
index 00000000..1f697fdb
--- /dev/null
+++ b/utils-test/src/main/java/org/onap/policy/common/utils/gson/GsonTestUtilsBuilder.java
@@ -0,0 +1,61 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * policy-management
+ * ================================================================================
+ * Copyright (C) 2017-2018 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 com.google.gson.GsonBuilder;
+import com.google.gson.TypeAdapterFactory;
+import org.onap.policy.common.gson.JacksonHandler;
+
+/**
+ * Used to builder a utility class.
+ */
+public class GsonTestUtilsBuilder {
+    private final GsonBuilder gsonBldr;
+
+    /**
+     * Constructs the object.
+     */
+    public GsonTestUtilsBuilder() {
+        gsonBldr = new GsonBuilder();
+
+        // register jackson behaviors with the builder
+        new JacksonHandler(gsonBldr);
+    }
+
+    /**
+     * Builds the utility.
+     *
+     * @return a new utility
+     */
+    public GsonTestUtils build() {
+        return new GsonTestUtils(gsonBldr.create());
+    }
+
+    /**
+     * Adds gson support for serializing a mock of a class.
+     *
+     * @param clazz mocked class to be supported
+     * @param sgson gson serializer
+     */
+    protected <T> void addMock(Class<T> clazz, TypeAdapterFactory sgson) {
+        gsonBldr.registerTypeAdapterFactory(sgson);
+    }
+}