fix(runtime/testing): format aggregate errors (#12183)

cli/tests/integration/test_tests.rs

@@ -180,3 +180,9 @@ itest!(shuffle_with_seed {
   exit_code: 0,
   output: "test/shuffle.out",
 });
+
+itest!(aggregate_error {
+  args: "test test/aggregate_error.ts",
+  exit_code: 1,
+  output: "test/aggregate_error.out",
+});

cli/tests/testdata/test/aggregate_error.out

@@ -0,0 +1,24 @@
+Check [WILDCARD]/testdata/test/aggregate_error.ts
+running 1 test from [WILDCARD]/testdata/test/aggregate_error.ts
+test aggregate ... FAILED ([WILDCARD])
+
+failures:
+
+aggregate
+AggregateError
+    Error: Error 1
+        at [WILDCARD]/testdata/test/aggregate_error.ts:2:18
+        [WILDCARD]
+    Error: Error 2
+        at [WILDCARD]/testdata/test/aggregate_error.ts:3:18
+        [WILDCARD]
+    at [WILDCARD]/testdata/test/aggregate_error.ts:5:9
+    at [WILDCARD]
+
+failures:
+
+	aggregate
+
+test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out ([WILDCARD])
+
+error: Test failed

cli/tests/testdata/test/aggregate_error.ts

@@ -0,0 +1,6 @@
+Deno.test("aggregate", function () {
+  const error1 = new Error("Error 1");
+  const error2 = new Error("Error 2");
+
+  throw new AggregateError([error1, error2]);
+});

runtime/js/40_testing.js

@@ -186,6 +186,23 @@ finishing test case.`;
     ArrayPrototypePush(tests, testDef);
   }
 
+  function formatFailure(error) {
+    if (error.errors) {
+      const message = error
+        .errors
+        .map((error) =>
+          inspectArgs([error]).replace(/^(?!\s*$)/gm, " ".repeat(4))
+        )
+        .join("\n");
+
+      return {
+        failed: error.name + "\n" + message + error.stack,
+      };
+    }
+
+    return { failed: inspectArgs([error]) };
+  }
+
   function createTestFilter(filter) {
     return (def) => {
       if (filter) {
@@ -213,10 +230,11 @@ finishing test case.`;
 
     try {
       await fn();
-      return "ok";
     } catch (error) {
-      return { "failed": inspectArgs([error]) };
+      return formatFailure(error);
     }
+
+    return "ok";
   }
 
   function getTestOrigin() {