add test

Author: JoeWang1127

java-sdk-logging/logback-extension/src/test/java/com/google/api/logging/SDKLoggingMdcJsonProviderTest.java

@@ -1,8 +1,12 @@
 package com.google.api.logging;
 
 import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyString;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoInteractions;
 import static org.mockito.Mockito.when;
 
 import ch.qos.logback.classic.spi.ILoggingEvent;
@@ -11,16 +15,24 @@
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 public class SDKLoggingMdcJsonProviderTest {
 
+  private SDKLoggingMdcJsonProvider provider = new SDKLoggingMdcJsonProvider();
+  private JsonGenerator generator = mock(JsonGenerator.class);
+  private ILoggingEvent event = mock(ILoggingEvent.class);
+  private Map<String, String> mdc;
+
+  @BeforeEach
+  void init() {
+    mdc = new HashMap<>();
+    when(event.getMDCPropertyMap()).thenReturn(mdc);
+  }
+
   @Test
-  void testWriteJsonFormat() throws IOException {
-    SDKLoggingMdcJsonProvider provider = new SDKLoggingMdcJsonProvider();
-    JsonGenerator generator = mock(JsonGenerator.class);
-    ILoggingEvent event = mock(ILoggingEvent.class);
-    Map<String, String> mdc = new HashMap<>();
+  void testWriteJsonStringToJsonTree() throws IOException {
     mdc.put(
         "json1",
         "{\n"
@@ -31,10 +43,29 @@ void testWriteJsonFormat() throws IOException {
             + "    \"state\": \"ACTIVE\"\n"
             + "  }\n"
             + "}");
-    when(event.getMDCPropertyMap()).thenReturn(mdc);
 
     provider.writeTo(generator, event);
     verify(generator).writeFieldName("json1");
     verify(generator).writeTree(any(JsonNode.class));
   }
+
+  @Test
+  void testWriteIllegalJsonFormatToString() throws IOException {
+    mdc.put(
+        "json1",
+        "{\n"
+            + "  \"@version\": \"1\",\n"
+            + "  \"textPayload\": \"Received response\",\n"
+            + "  \"response.payload\": {\n"
+            + "    \"name\": \"example\",\n"
+            + "    \"state\": \"ACTIVE\",\n" // the last semicolon is redundant.
+            + "  }\n"
+            + "}");
+
+
+    provider.writeTo(generator, event);
+    verify(generator).writeFieldName("json1");
+    verify(generator, never()).writeTree(any(JsonNode.class));
+    verify(generator).writeObject(anyString());
+  }
 }