Implement #22: add class and message fields to JSON

Author: vitalijr2

json-logger/src/main/java/uk/bot_by/aws_lambda/slf4j/json_output/JSONLoggerOutput.java

@@ -47,6 +47,8 @@ public class JSONLoggerOutput implements AWSLambdaLoggerOutput {
   private static final Long START_TIME = System.currentTimeMillis();
   private static final String THREAD_ID = "thread-id";
   private static final String THREAD_NAME = "thread-name";
+  private static final String THROWABLE_CLASS = "throwable-class";
+  private static final String THROWABLE_MESSAGE = "throwable-message";
   private static final String TIMESTAMP = "timestamp";
 
   private static void addLevel(Level level, JSONObject jsonObject) {
@@ -76,6 +78,20 @@ private static void addThread(AWSLambdaLoggerConfiguration configuration, JSONOb
     }
   }
 
+  private static void addThrowable(Throwable throwable, JSONObject jsonObject) {
+    if (nonNull(throwable)) {
+      jsonObject.put(THROWABLE_CLASS, throwable.getClass().getName());
+      if (nonNull(throwable.getMessage())) {
+        jsonObject.put(THROWABLE_MESSAGE, throwable.getMessage());
+      }
+
+      var stackTraceOutputStream = new ByteArrayOutputStream();
+
+      throwable.printStackTrace(new PrintStream(stackTraceOutputStream));
+      jsonObject.put(STACK_TRACE, stackTraceOutputStream);
+    }
+  }
+
   @SuppressWarnings("ConstantConditions")
   private static void addTimestamp(AWSLambdaLoggerConfiguration configuration,
       JSONObject jsonObject) {
@@ -130,12 +146,7 @@ void log(@NotNull AWSLambdaLoggerConfiguration configuration, @NotNull LambdaLog
     addLevel(level, jsonObject);
     addLogName(configuration, jsonObject);
     jsonObject.put(MESSAGE, message);
-    if (nonNull(throwable)) {
-      var stackTraceOutputStream = new ByteArrayOutputStream();
-
-      throwable.printStackTrace(new PrintStream(stackTraceOutputStream));
-      jsonObject.put(STACK_TRACE, stackTraceOutputStream);
-    }
+    addThrowable(throwable, jsonObject);
 
     synchronized (START_TIME) {
       lambdaLogger.log(jsonObject.toString());

json-logger/src/test/java/uk/bot_by/aws_lambda/slf4j/json_output/JSONLoggerOutputTest.java

@@ -1,9 +1,11 @@
 package uk.bot_by.aws_lambda.slf4j.json_output;
 
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.core.IsEqual.equalTo;
 import static org.hamcrest.core.StringStartsWith.startsWith;
 import static org.junit.jupiter.api.Assertions.assertAll;
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
@@ -248,16 +250,17 @@ void showLogName() {
         stringCaptor.getValue(), true);
   }
 
-  @DisplayName("Print a stack trace")
+  @DisplayName("Print a throwable")
   @Test
-  void stackTrace() {
+  void throwableWithMessage() {
     // given
     var throwable = mock(Throwable.class);
 
     doAnswer(invocationOnMock -> {
       invocationOnMock.getArgument(0, PrintStream.class).println("*");
       return null;
     }).when(throwable).printStackTrace(isA(PrintStream.class));
+    when(throwable.getMessage()).thenReturn("test message");
     when(configuration.requestId()).thenReturn("request#");
 
     // when
@@ -269,7 +272,40 @@ void stackTrace() {
 
     var jsonObject = new JSONObject(stringCaptor.getValue());
 
-    assertAll("thread ID", () -> assertTrue(jsonObject.has("stack-trace"), "field exists"),
+    assertAll("throwable", () -> assertTrue(jsonObject.has("throwable-class")),
+        () -> assertThat("class", jsonObject.getString("throwable-class"),
+            equalTo("java.lang.Throwable")), () -> assertTrue(jsonObject.has("throwable-message")),
+        () -> assertThat("message", jsonObject.getString("throwable-message"),
+            equalTo("test message")),
+        () -> assertTrue(jsonObject.has("stack-trace"), "field exists"),
+        () -> assertThat("field value", jsonObject.getString("stack-trace"), startsWith("*")));
+  }
+
+  @DisplayName("Print a throwable without message")
+  @Test
+  void throwableWithoutMessage() {
+    // given
+    var throwable = mock(Throwable.class);
+
+    doAnswer(invocationOnMock -> {
+      invocationOnMock.getArgument(0, PrintStream.class).println("*");
+      return null;
+    }).when(throwable).printStackTrace(isA(PrintStream.class));
+    when(configuration.requestId()).thenReturn("request#");
+
+    // when
+    loggerOutput.log(configuration, lambdaLogger, null, Level.ERROR, "test error message",
+        throwable);
+
+    // then
+    verify(lambdaLogger).log(stringCaptor.capture());
+
+    var jsonObject = new JSONObject(stringCaptor.getValue());
+
+    assertAll("throwable", () -> assertTrue(jsonObject.has("throwable-class")),
+        () -> assertThat("class", jsonObject.getString("throwable-class"),
+            equalTo("java.lang.Throwable")), () -> assertFalse(jsonObject.has("throwable-message")),
+        () -> assertTrue(jsonObject.has("stack-trace"), "field exists"),
         () -> assertThat("field value", jsonObject.getString("stack-trace"), startsWith("*")));
   }