Fix watcher behaviour (#344)

This fixes the watcher regression in #342, and includes a full end-to-end test of the watching behaviour to avoid any further regressions in future.

src/cli.js

@@ -34,8 +34,9 @@ Options:
 let api = false;
 if (require.main === module) {
   runCmd(process.argv.slice(2), process.stdout, process.stderr)
-  .then(() => {
-    process.exit()
+  .then((watching) => {
+    if (!watching)
+      process.exit();
   })
   .catch(e => {
     if (!e.silent)
@@ -315,6 +316,7 @@ async function runCmd (argv, stdout, stderr) {
           startTime = Date.now();
           stdout.write('File change, rebuilding...\n');
         });
+        return true;
       } else {
         return ncc.then(handler);
       }

src/index.js

@@ -226,18 +226,17 @@ module.exports = (
   else {
     let cachedResult;
     watcher = compiler.watch({}, (err, stats) => {
-      if (err) return reject(err);
       if (err)
         return watchHandler({ err });
       if (stats.hasErrors())
         return watchHandler({ err: stats.toString() });
-      const { code, map, assets } = finalizeHandler();
+      const returnValue = finalizeHandler();
       // clear output file system
       mfs.data = {};
       if (watchHandler)
-        watchHandler({ code, map, assets, err: null });
+        watchHandler(returnValue);
       else
-        cachedResult = { code, map, assets};
+        cachedResult = returnValue;
     });
     let closed = false;
     return {

test/cli.js

@@ -24,5 +24,10 @@
   {
     args: ["run", "--watch", "test/integration/test.ts"],
     expect: { code: 2 }
+  },
+  {
+    args: ["build", "-o", "tmp", "--watch", "test/fixtures/no-dep.js"],
+    timeout: 500,
+    expect: { timeout: true }
   }
 ]

test/fixtures/no-dep.js

@@ -0,0 +1 @@
+console.log('asdf');

test/index.test.js

@@ -42,11 +42,21 @@ for (const cliTest of eval(fs.readFileSync(__dirname + "/cli.js").toString())) {
     ps.stderr.on("data", chunk => stderr += chunk.toString());
     ps.stdout.on("data", chunk => stdout += chunk.toString());
     const expected = cliTest.expect || { code: 0 };
+    let timedOut = false;
+    if (cliTest.timeout)
+      setTimeout(() => {
+        timedOut = true;
+        ps.kill();
+      }, cliTest.timeout);
     const code = await new Promise(resolve => ps.on("close", resolve));
     if (typeof expected === "function")
-      expect(expected(code, stdout, stderr)).toBe(true);
-    else if ("code" in expected)
-      expect(code).toBe(expected.code);
+      expect(expected(code, stdout, stderr, timedOut)).toBe(true);
+    else {
+      if ("code" in expected)
+        expect(code).toBe(expected.code);
+      if ("timeout" in expected)
+        expect(timedOut).toBe(true);
+    }
   });
 }