cmd/pkgserver/ui_test: add JSON reporter for go test integration

cmd/pkgserver/ui_test/lib/test.ts

@@ -18,6 +18,7 @@ export class TestRegistrar {
     }
 
     run(reporter: Reporter) {
+        reporter.register(this.#suites);
         for (const suite of this.#suites) {
             for (const c of suite.children) runTests(reporter, [suite.name], c);
         }
@@ -132,19 +133,26 @@ function extractExceptionString(e: any): string {
 // Reporting
 
 export interface Reporter {
+    register(suites: TestGroup[]): void;
     update(path: string[], result: TestResult): void;
     finalize(): void;
 }
 
 export class NoOpReporter implements Reporter {
+    suites: TestGroup[];
     results: ({ path: string[] } & TestResult)[];
     finalized: boolean;
 
     constructor() {
+        this.suites = [];
         this.results = [];
         this.finalized = false;
     }
 
+    register(suites: TestGroup[]) {
+        this.suites = suites;
+    }
+
     update(path: string[], result: TestResult) {
         this.results.push({ path, ...result });
     }
@@ -177,6 +185,8 @@ export class StreamReporter implements Reporter {
         return this.counts.successes > 0 && this.counts.failures === 0;
     }
 
+    register(suites: TestGroup[]) {}
+
     update(path: string[], result: TestResult) {
         if (path.length === 0) throw new RangeError("path is empty");
         const pathStr = path.join(SEP);
@@ -244,6 +254,8 @@ function assertGetElementById(id: string): HTMLElement {
 }
 
 export class DOMReporter implements Reporter {
+    register(suites: TestGroup[]) {}
+
     update(path: string[], result: TestResult) {
         if (path.length === 0) throw new RangeError("path is empty");
         const counter = assertGetElementById(result.success ? "successes" : "failures");
@@ -292,3 +304,31 @@ export class DOMReporter implements Reporter {
 
     finalize() {}
 }
+
+interface GoNode {
+    name: string;
+    subtests?: GoNode[];
+}
+
+// Used to display results via `go test`, via some glue code from the Go side.
+export class GoTestReporter implements Reporter {
+    register(suites: TestGroup[]) {
+        console.log(JSON.stringify(suites.map(GoTestReporter.serialize)));
+    }
+
+    // Convert a test tree into the one expected by the Go code.
+    static serialize(node: TestTree): GoNode {
+        return {
+            name: node.name,
+            subtests: "children" in node ? node.children.map(GoTestReporter.serialize) : undefined,
+        };
+    }
+
+    update(path: string[], result: TestResult) {
+        console.log(JSON.stringify({ path, ...result }));
+    }
+
+    finalize() {
+        console.log("null");
+    }
+}