BetterThanTomorrow#1007: show diff between expected and actual in test runner

Author: SebastianAas

src/nrepl/cider.ts

@@ -1,3 +1,4 @@
+import { diff } from 'semver';
 // https://github.com/clojure-emacs/cider-nrepl/blob/a740583c3aa8b582f3097611787a276775131d32/src/cider/nrepl/middleware/test.clj#L45
 export interface TestSummary {
   ns: number;
@@ -142,6 +143,24 @@ export function lineInformation(result: TestResult): string {
   return ` (${result.file}:${result.line})`;
 }
 
+function testDiffInformation(result: TestResult): string[] {
+  const diffs = result.diffs;
+  const messages: string[] = [];
+
+  if (diffs && Array.isArray(diffs)) {
+    diffs.forEach((diffPair: [string, string]) => {
+      if (Array.isArray(diffPair) && diffPair.length === 2) {
+        messages.push(`; expected:\n${diffPair[0]}`);
+        messages.push(`; actual:\n${diffPair[1]}`);
+      } else {
+        console.warn('Invalid diff pair format:', diffPair);
+      }
+    });
+  }
+
+  return messages;
+}
+
 // Return a detailed message about why a test failed.
 // If the test passed, return the empty string.
 // The message contains "comment" lines that are prepended with ;
@@ -167,11 +186,18 @@ export function detailedMessage(result: TestResult): string | undefined {
     if (message) {
       messages.push(`; ${message}`);
     }
-    if (result.expected) {
-      messages.push(`; expected:\n${result.expected}`);
-    }
-    if (result.actual) {
-      messages.push(`; actual:\n${result.actual}`);
+
+    const diffMessages = testDiffInformation(result);
+
+    if (diffMessages.length > 0) {
+      messages.push(...diffMessages);
+    } else {
+      if (result.expected) {
+        messages.push(`; expected:\n${result.expected}`);
+      }
+      if (result.actual) {
+        messages.push(`; actual:\n${result.actual}`);
+      }
     }
   }
   return messages.length > 0 ? messages.join('\n') : undefined;

src/testRunner.ts

@@ -139,6 +139,7 @@ async function onTestResult(
         run.errored(assertion, new vscode.TestMessage(cider.shortMessage(result)));
         break;
       case 'fail':
+        run.failed(assertion, new vscode.TestMessage(cider.detailedMessage(result)));
       default:
         run.failed(assertion, new vscode.TestMessage(cider.shortMessage(result)));
         break;