Remove duplicate code from type adapters

Extracted a common superclass, StringTypeAdapter, out of the gson type
adapter classes.

Issue-ID: POLICY-2914
Change-Id: I4bbd2a6e8372e7f42c4952ba9ff03eed97473fb2
Signed-off-by: Jim Hahn <jrh3@att.com>

3 files changed, 96 insertions, 22 deletions

diff --git a/gson/src/test/java/org/onap/policy/common/gson/InstantTypeAdapterTest.java b/gson/src/test/java/org/onap/policy/common/gson/InstantTypeAdapterTest.java
index 97219d0d..68f54ed8 100644
--- a/gson/src/test/java/org/onap/policy/common/gson/InstantTypeAdapterTest.java
+++ b/gson/src/test/java/org/onap/policy/common/gson/InstantTypeAdapterTest.java
@@ -2,7 +2,7 @@
  * ============LICENSE_START=======================================================
  * ONAP
  * ================================================================================
- * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
+ * Copyright (C) 2020-2021 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.
@@ -53,16 +53,6 @@ public class InstantTypeAdapterTest {
         String json2 = json.replace("2020", "invalid-date");
         assertThatThrownBy(() -> gson.fromJson(json2, InterestingFields.class)).isInstanceOf(JsonParseException.class)
                         .hasMessageContaining("invalid date");
-
-        // null output
-        data.instant = null;
-        json = gson.toJson(data);
-        data2 = gson.fromJson(json, InterestingFields.class);
-        assertEquals(data.toString(), data2.toString());
-
-        // null input
-        data2 = gson.fromJson("{\"instant\":null}", InterestingFields.class);
-        assertEquals(data.toString(), data2.toString());
     }
 
 
diff --git a/gson/src/test/java/org/onap/policy/common/gson/StringTypeAdapterTest.java b/gson/src/test/java/org/onap/policy/common/gson/StringTypeAdapterTest.java
new file mode 100644
index 00000000..f35677cd
--- /dev/null
+++ b/gson/src/test/java/org/onap/policy/common/gson/StringTypeAdapterTest.java
@@ -0,0 +1,94 @@
+/*-
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2021 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.gson;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+import static org.junit.Assert.assertEquals;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.JsonParseException;
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.ToString;
+import org.junit.Test;
+
+public class StringTypeAdapterTest {
+    private static Gson gson = new GsonBuilder().registerTypeAdapter(MyData.class, new MyAdapter()).create();
+    private static final int TEST_NUM1 = 10;
+    private static final int TEST_NUM3 = 30;
+
+    @Test
+    public void test() {
+        InterestingFields data = new InterestingFields();
+        data.data1 = new MyData(TEST_NUM1);
+        data.data2 = null;
+        data.data3 = new MyData(TEST_NUM3);
+
+        String json = gson.toJson(data);
+
+        // instant should be encoded as a number, without quotes
+        assertThat(json).contains("10", "30");
+
+        InterestingFields data2 = gson.fromJson(json, InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+
+        // try when the string is invalid
+        String json2 = json.replace("30", "invalid-value");
+        assertThatThrownBy(() -> gson.fromJson(json2, InterestingFields.class)).isInstanceOf(JsonParseException.class)
+                        .hasMessageContaining("invalid data");
+
+        // null output
+        data = new InterestingFields();
+        json = gson.toJson(data);
+        data2 = gson.fromJson(json, InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+
+        // null input
+        data2 = gson.fromJson("{\"data1\":null, \"data1\":null, \"data1\":null}", InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+
+        // empty input
+        data2 = gson.fromJson("{}", InterestingFields.class);
+        assertEquals(data.toString(), data2.toString());
+    }
+
+    @Getter
+    @ToString
+    @AllArgsConstructor
+    private static class MyData {
+        private int num;
+    }
+
+    @ToString
+    private static class InterestingFields {
+        private MyData data1;
+        private MyData data2;
+        private MyData data3;
+    }
+
+    private static class MyAdapter extends StringTypeAdapter<MyData> {
+        public MyAdapter() {
+            super("data", string -> new MyData(Integer.parseInt(string)), data -> String.valueOf(data.num));
+        }
+    }
+}
diff --git a/gson/src/test/java/org/onap/policy/common/gson/ZonedDateTimeTypeAdapterTest.java b/gson/src/test/java/org/onap/policy/common/gson/ZonedDateTimeTypeAdapterTest.java
index 766a979d..032533eb 100644
--- a/gson/src/test/java/org/onap/policy/common/gson/ZonedDateTimeTypeAdapterTest.java
+++ b/gson/src/test/java/org/onap/policy/common/gson/ZonedDateTimeTypeAdapterTest.java
@@ -2,7 +2,7 @@
  * ============LICENSE_START=======================================================
  * ONAP
  * ================================================================================
- * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
+ * Copyright (C) 2020-2021 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.
@@ -53,16 +53,6 @@ public class ZonedDateTimeTypeAdapterTest {
         String json2 = json.replace("2020", "invalid-date");
         assertThatThrownBy(() -> gson.fromJson(json2, InterestingFields.class)).isInstanceOf(JsonParseException.class)
                         .hasMessageContaining("invalid date");
-
-        // null output
-        data.date = null;
-        json = gson.toJson(data);
-        data2 = gson.fromJson(json, InterestingFields.class);
-        assertEquals(data.toString(), data2.toString());
-
-        // null input
-        data2 = gson.fromJson("{\"date\":null}", InterestingFields.class);
-        assertEquals(data.toString(), data2.toString());
     }