Update FE test script

- Don't fail when no tests match
- Print the cmd prefix for each line in it's data
- Update exit code handling
- Add colors to summary message

scripts/frontend/test.js

 #!/usr/bin/env node
 
-const program = require('commander');
 const { spawn } = require('child_process');
+const { EOL } = require('os');
+const program = require('commander');
+const chalk = require('chalk');
 
 const JEST_ROUTE = 'spec/frontend';
 const KARMA_ROUTE = 'spec/javascripts';
 const COMMON_ARGS = ['--colors'];
+const JEST_ARGS = ['--passWithNoTests'];
+const KARMA_ARGS = ['--no-fail-on-empty-test-suite'];
+const SUCCESS_CODE = 0;
 
 program
   .version('0.1.0')
@@ -13,18 +18,40 @@ program
   .option('-p, --parallel', 'Run tests suites in parallel')
   .parse(process.argv);
 
+const isSuccess = code => code === SUCCESS_CODE;
+
+const combineExitCodes = codes => {
+  const firstFail = codes.find(x => !isSuccess(x));
+
+  return firstFail === undefined ? SUCCESS_CODE : firstFail;
+};
+
+const skipIfFail = fn => code => (isSuccess(code) ? fn() : code);
+
+const endWithEOL = str => (str[str.length - 1] === '\n' ? str : `${str}${EOL}`);
+
 const runTests = paths => {
   if (program.parallel) {
-    return Promise.all([runJest(paths), runKarma(paths)]);
+    return Promise.all([runJest(paths), runKarma(paths)]).then(combineExitCodes);
   } else {
-    return runJest(paths).then(() => runKarma(paths));
+    return runJest(paths).then(skipIfFail(() => runKarma(paths)));
   }
 };
 
-const spawnPromise = (cmd, args) => {
+const spawnYarnScript = (cmd, args) => {
   return new Promise((resolve, reject) => {
     const proc = spawn('yarn', ['run', cmd, ...args]);
-    const output = data => `${cmd}: ${data}`;
+    const output = data => {
+      const text = data
+        .toString()
+        .split(/\r?\n/g)
+        .map((line, idx, { length }) =>
+          idx === length - 1 && !line ? line : `${chalk.gray(cmd)}: ${line}`,
+        )
+        .join(EOL);
+
+      return endWithEOL(text);
+    };
 
     proc.stdout.on('data', data => {
       process.stdout.write(output(data));
@@ -35,22 +62,22 @@ const spawnPromise = (cmd, args) => {
     });
 
     proc.on('close', code => {
-      process.stdout.write(`${cmd} exited with code ${code}`);
-      if (code === 0) {
-        resolve();
-      } else {
-        reject();
-      }
+      process.stdout.write(output(`exited with code ${code}`));
+
+      // We resolve even on a failure code because a `reject` would cause
+      // Promise.all to reject immediately (without waiting for other promises)
+      // to finish.
+      resolve(code);
     });
   });
 };
 
 const runJest = args => {
-  return spawnPromise('jest', [...COMMON_ARGS, ...toJestArgs(args)]);
+  return spawnYarnScript('jest', [...JEST_ARGS, ...COMMON_ARGS, ...toJestArgs(args)]);
 };
 
 const runKarma = args => {
-  return spawnPromise('karma', [...COMMON_ARGS, ...toKarmaArgs(args)]);
+  return spawnYarnScript('karma', [...KARMA_ARGS, ...COMMON_ARGS, ...toKarmaArgs(args)]);
 };
 
 const replacePath = to => path =>
@@ -59,18 +86,28 @@ const replacePath = to => path =>
     .replace(KARMA_ROUTE, to)
     .replace('app/assets/javascripts', to);
 
-const toJestArgs = paths => paths.map(replacePath(JEST_ROUTE));
+const replacePathForJest = replacePath(JEST_ROUTE);
+
+const replacePathForKarma = replacePath(KARMA_ROUTE);
+
+const toJestArgs = paths => paths.map(replacePathForJest);
 
 const toKarmaArgs = paths =>
-  paths.map(replacePath(KARMA_ROUTE)).reduce((acc, current) => acc.concat('-f', current), []);
+  paths.reduce((acc, path) => acc.concat('-f', replacePathForKarma(path)), []);
 
 const main = paths => {
-  runTests(paths)
-    .then(() => {
-      console.log('All tests passed!');
-    })
-    .catch(() => {
-      console.log('Some tests failed...');
+  runTests(paths).then(code => {
+    console.log('~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~');
+    if (isSuccess(code)) {
+      console.log(chalk.bgGreen(chalk.black('All tests passed :)')));
+    } else {
+      console.log(chalk.bgRed(chalk.white(`Some tests failed :(`)));
+    }
+    console.log('~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~');
+
+    if (!isSuccess(code)) {
+      process.exit(code);
+    }
   });
 };