Adjust test-adapter to display diffs only for failing tests

extensions/ql-vscode/src/cli.ts

@@ -123,6 +123,7 @@ export interface TestCompleted {
   expected: string;
   diff: string[] | undefined;
   failureDescription?: string;
+  failureStage?: string;
 }
 
 /**

extensions/ql-vscode/src/test-adapter.ts

@@ -294,7 +294,9 @@ export class QLTestAdapter extends DisposableObject implements TestAdapter {
           : 'failed';
       let message: string | undefined;
       if (event.failureDescription || event.diff?.length) {
-        message = ['', `${state}: ${event.test}`, event.failureDescription || event.diff?.join('\n'), ''].join('\n');
+        message = event.failureStage === 'RESULT'
+          ? ['', `${state}: ${event.test}`, event.failureDescription || event.diff?.join('\n'), ''].join('\n')
+          : ['', `${event.failureStage?.toLowerCase()} error: ${event.test}`, event.failureDescription || `${event.messages[0].severity}: ${event.messages[0].message}`, ''].join('\n');
         void testLogger.log(message);
       }
       this._testStates.fire({

extensions/ql-vscode/src/vscode-tests/no-workspace/test-adapter.test.ts

@@ -96,7 +96,7 @@ describe('test-adapter', () => {
       type: 'test',
       state: 'errored',
       test: gPath,
-      message: `\nerrored: ${gPath}\npqr\nxyz\n`,
+      message: `\ncompilation error: ${gPath}\nERROR: abc\n`,
       decorations: [
         { line: 1, message: 'abc' }
       ]
@@ -149,14 +149,16 @@ describe('test-adapter', () => {
           pass: false,
           diff: ['pqr', 'xyz'],
           // a compile error
+          failureStage: 'COMPILATION',
           messages: [
-            { position: { line: 1 }, message: 'abc' }
+            { position: { line: 1 }, message: 'abc', severity: 'ERROR' }
           ]
         });
         yield Promise.resolve({
           test: Uri.parse('file:/ab/c/e/f/h.ql').fsPath,
           pass: false,
           diff: ['jkh', 'tuv'],
+          failureStage: 'RESULT',
           messages: []
         });
       })()