2 files changed, 55 insertions, 7 deletions

diff --git a/utils/src/main/java/org/onap/policy/common/utils/coder/StandardCoder.java b/utils/src/main/java/org/onap/policy/common/utils/coder/StandardCoder.java
index 7f5e3b85..3b4f3c23 100644
--- a/utils/src/main/java/org/onap/policy/common/utils/coder/StandardCoder.java
+++ b/utils/src/main/java/org/onap/policy/common/utils/coder/StandardCoder.java
@@ -1,8 +1,8 @@
-/*
+/*-
  * ============LICENSE_START=======================================================
  * ONAP
  * ================================================================================
- * Copyright (C) 2019-2020 AT&T Intellectual Property. All rights reserved.
+ * Copyright (C) 2019-2021 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.
@@ -40,6 +40,7 @@ import java.io.Writer;
 import java.nio.charset.StandardCharsets;
 import java.util.List;
 import java.util.Map;
+import org.apache.commons.lang3.StringUtils;
 import org.onap.policy.common.gson.DoubleConverter;
 import org.onap.policy.common.gson.GsonMessageBodyHandler;
 
@@ -341,8 +342,17 @@ public class StandardCoder implements Coder {
      * @param json json string to be decoded
      * @param clazz class of object to be decoded
      * @return the object represented by the given json string
+     * @throws CoderException if the source is empty
      */
-    protected <T> T fromJson(String json, Class<T> clazz) {
+    protected <T> T fromJson(String json, Class<T> clazz) throws CoderException {
+        if (json == null) {
+            return null;
+        }
+
+        if (StringUtils.isBlank(json)) {
+            throw new CoderException("source string is empty");
+        }
+
         return convertFromDouble(clazz, gson.fromJson(json, clazz));
     }
 
@@ -352,9 +362,16 @@ public class StandardCoder implements Coder {
      * @param source source from which to read the json string to be decoded
      * @param clazz class of object to be decoded
      * @return the object represented by the given json string
+     * @throws CoderException if the source is empty
      */
-    protected <T> T fromJson(Reader source, Class<T> clazz) {
-        return convertFromDouble(clazz, gson.fromJson(source, clazz));
+    protected <T> T fromJson(Reader source, Class<T> clazz) throws CoderException {
+        T object = gson.fromJson(source, clazz);
+
+        if (object == null) {
+            throw new CoderException("source is empty");
+        }
+
+        return convertFromDouble(clazz, object);
     }
 
     /**
diff --git a/utils/src/test/java/org/onap/policy/common/utils/coder/StandardCoderTest.java b/utils/src/test/java/org/onap/policy/common/utils/coder/StandardCoderTest.java
index a468f0b4..be588a40 100644
--- a/utils/src/test/java/org/onap/policy/common/utils/coder/StandardCoderTest.java
+++ b/utils/src/test/java/org/onap/policy/common/utils/coder/StandardCoderTest.java
@@ -1,8 +1,8 @@
-/*
+/*-
  * ============LICENSE_START=======================================================
  * ONAP PAP
  * ================================================================================
- * Copyright (C) 2019-2020 AT&T Intellectual Property. All rights reserved.
+ * Copyright (C) 2019-2021 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.
@@ -20,6 +20,7 @@
 
 package org.onap.policy.common.utils.coder;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
@@ -263,6 +264,8 @@ public class StandardCoderTest {
 
     @Test
     public void testToJsonTree_testFromJsonJsonElementClassT() throws Exception {
+        assertThat(coder.fromJson((JsonElement) null, MyMap.class)).isNull();
+
         MyMap map = new MyMap();
         map.props = new LinkedHashMap<>();
         map.props.put("jel keyA", "jel valueA");
@@ -278,6 +281,34 @@ public class StandardCoderTest {
     }
 
     @Test
+    public void testFromJsonStringClassT() throws Exception {
+        assertThat(coder.fromJson((String) null, MyMap.class)).isNull();
+
+        String json = "{'props': {'str keyA': 'str valueA', 'str keyB':'str valueB'}}".replace('\'', '"');
+
+        Object result = coder.fromJson(json, MyMap.class);
+
+        assertNotNull(result);
+        assertEquals("{str keyA=str valueA, str keyB=str valueB}", result.toString());
+
+        assertThatThrownBy(() -> coder.fromJson("", MyMap.class)).isInstanceOf(CoderException.class)
+                        .hasMessageContaining("empty");
+    }
+
+    @Test
+    public void testFromJsonReaderClassT() throws Exception {
+        String json = "{'props': {'str keyA': 'str valueA', 'str keyB':'str valueB'}}".replace('\'', '"');
+
+        Object result = coder.fromJson(new StringReader(json), MyMap.class);
+
+        assertNotNull(result);
+        assertEquals("{str keyA=str valueA, str keyB=str valueB}", result.toString());
+
+        assertThatThrownBy(() -> coder.fromJson(new StringReader(""), MyMap.class)).isInstanceOf(CoderException.class)
+                        .hasMessageContaining("empty");
+    }
+
+    @Test
     public void testConvertFromDouble() throws Exception {
         String text = "[listA, {keyA=100}, 200]";
         assertEquals(text, coder.decode(text, Object.class).toString());