fix: Don't exit synchronously when there still might be async I/O (#90)

See https://nodejs.org/api/process.html#processexitcode for an
explanation of process.exit and process.exitCode and
https://nodejs.org/api/process.html#a-note-on-process-io for an
explanation when I/O might be sync or async.

Additionally writes a newline after format "json" has been written. This
prevents strange behavior in at least zsh when output is not terminated
by a newline.

src/cli/base.ts

@@ -133,6 +133,7 @@ async function handleLint(argv: ArgumentsCamelCase<LinterArg>) {
 	if (format === "json") {
 		const jsonFormatter = new Json();
 		process.stdout.write(jsonFormatter.format(res, details));
+		process.stdout.write("\n");
 	} else if (format === "" || format === "stylish") {
 		const textFormatter = new Text();
 		process.stderr.write(textFormatter.format(res, details));
@@ -144,7 +145,7 @@ async function handleLint(argv: ArgumentsCamelCase<LinterArg>) {
 
 	if (res.some((file) => !!file.errorCount)) {
 		// At least one error is reported. Exit with non-zero exit code.
-		process.exit(1);
+		process.exitCode = 1;
 	}
 }
 

test/lib/cli/base.integration.ts

@@ -38,14 +38,20 @@ test.serial("ui5lint --format json", async (t) => {
 
 	t.is(consoleLogStub.callCount, 0, "console.log should not be used");
 	t.true(processCwdStub.callCount > 0, "process.cwd was called");
-	t.is(processStdoutWriteStub.callCount, 1, "process.stdout.write is only used once");
-	t.is(processExitStub.callCount, 1, "process.exit got called once");
-	t.is(processExitStub.firstCall.firstArg, 1, "process.exit got called with exit code 1");
+	t.is(processStdoutWriteStub.callCount, 2, "process.stdout.write was called twice");
+	t.is(processExitStub.callCount, 0, "process.exit got never called");
+	t.is(process.exitCode, 1, "process.exitCode was set to 1");
+	// cleanup: reset exit code in order not to fail the test (it cannot be stubbed with sinon)
+	process.exitCode = 0;
 
-	const resultProcessStdout = processStdoutWriteStub.firstCall.firstArg;
+	const resultProcessStdoutJSON = processStdoutWriteStub.firstCall.firstArg;
 	let parsedJson: LintResult[];
 
-	t.notThrows(() => parsedJson = JSON.parse(resultProcessStdout), "Output of process.stdout.write is JSON-formatted");
+	t.notThrows(() => parsedJson = JSON.parse(resultProcessStdoutJSON),
+		"Output of process.stdout.write is JSON-formatted");
 	t.true(Array.isArray(parsedJson!), "The parsed JSON output is a LintResult array");
 	t.true(parsedJson!.length > 0, "The parsed JSON output contains at least one result");
+
+	const resultProcessStdoutNL = processStdoutWriteStub.secondCall.firstArg;
+	t.is(resultProcessStdoutNL, "\n", "second write only adds a single newline");
 });