test: Add more tests

Author: Abhi347

src/test/java/com/spotify/github/tracing/OpenTelemetrySpanTest.java

@@ -27,8 +27,7 @@
 
 import java.util.Collections;
 
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.*;
 
 class OpenTelemetrySpanTest {
     private final io.opentelemetry.api.trace.Span wrapped = mock(io.opentelemetry.api.trace.Span.class);
@@ -66,4 +65,26 @@ public void failOnServerError() {
         verify(wrapped).end();
     }
 
+    @Test
+    public void failWithNullThrowable() {
+        final Span span = new OpenTelemetrySpan(wrapped);
+        span.failure(null);
+        span.close();
+
+        verify(wrapped).setStatus(StatusCode.UNSET);
+        verify(wrapped, never()).setAttribute(anyString(), any());
+        verify(wrapped).end();
+    }
+
+    @Test
+    public void failWithNonRequestNotOkException() {
+        final Span span = new OpenTelemetrySpan(wrapped);
+        span.failure(new RuntimeException("Unexpected error"));
+        span.close();
+
+        verify(wrapped).setStatus(StatusCode.UNSET);
+        verify(wrapped, never()).setAttribute("http.status_code", 404);
+        verify(wrapped, never()).setAttribute("error", true);
+        verify(wrapped).end();
+    }
 }