Minor, add toString() for debug

compiler/tests/org/jetbrains/kotlin/checkers/BaseDiagnosticsTest.java

@@ -303,6 +303,11 @@ public abstract class BaseDiagnosticsTest
         public int compareTo(@NotNull TestModule module) {
             return name.compareTo(module.getName());
         }
+
+        @Override
+        public String toString() {
+            return getName();
+        }
     }
 
     public static class DiagnosticTestLanguageVersionSettings implements LanguageVersionSettings {
@@ -510,5 +515,10 @@ public abstract class BaseDiagnosticsTest
             }
             return jvmSignatureDiagnostics;
         }
+
+        @Override
+        public String toString() {
+            return jetFile.getName();
+        }
     }
 }