fix: Add cleanup for Trace context (#266)

* fix: fixing tests to cleanup trace context

Previously we didn't cleanup trace context so it could cause side effects to some tests as a result of added label in trace context tests. To mitigate this, we added a method to cleanup trace context from MDC as well as invoke it before every test

* fix: fixing tests to cleanup trace context

Previously we didn't cleanup trace context so it could cause side effects to some tests as a result of added label in trace context tests. To mitigate this, we added a method to cleanup trace context from MDC as well as invoke it before every test

* fix: lint

Author: Simon Zeltser

src/main/java/com/google/cloud/logging/logback/TraceLoggingEventEnhancer.java

@@ -35,6 +35,10 @@ public static void setCurrentTraceId(String id) {
     MDC.put(TRACE_ID, id);
   }
 
+  /** Clearing a trace Id from the MDC */
+  public static void clearTraceId() {
+    MDC.remove(TRACE_ID);
+  }
   /**
    * Get the Trace ID associated with any logging done by the current thread.
    *

src/test/java/com/google/cloud/logging/logback/TraceLoggingEventEnhancerTest.java

@@ -21,6 +21,7 @@
 import ch.qos.logback.classic.spi.LoggingEvent;
 import com.google.cloud.logging.LogEntry;
 import com.google.cloud.logging.Payload.StringPayload;
+import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 
@@ -32,6 +33,11 @@ public void setUp() {
     classUnderTest = new TraceLoggingEventEnhancer();
   }
 
+  @After
+  public void tearDown() {
+    TraceLoggingEventEnhancer.clearTraceId();
+  }
+
   @Test
   public void testEnhanceLogEntry() {
     // setup