Replace "until" test helper with a continous run with control flow

jestjs · Nov 9, 2018 · 9e54fbd · 9e54fbd
1 parent b44e7f2
commit 9e54fbd
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Showing 2 changed files with 85 additions and 40 deletions.
diff --git a/e2e/__tests__/detect_open_handles.js b/e2e/__tests__/detect_open_handles.js
@@ -8,7 +8,7 @@
  */
 'use strict';
 
-import runJest, {until} from '../runJest';
+import runJest, {runContinuous} from '../runJest';
 
 try {
   // $FlowFixMe: Node core
@@ -29,33 +29,36 @@ function getTextAfterTest(stderr) {
 }
 
 it('prints message about flag on slow tests', async () => {
-  const {stderr} = await until(
-    'detect-open-handles',
-    ['outside'],
-    'Jest did not exit one second after the test run has completed.',
+  const run = runContinuous('detect-open-handles', ['outside']);
+  await run.waitUntil(({stderr}) =>
+    stderr.includes(
+      'Jest did not exit one second after the test run has completed.',
+    ),
   );
+
+  const {stderr} = await run.end();
+
   const textAfterTest = getTextAfterTest(stderr);
 
   expect(textAfterTest).toMatchSnapshot();
 });
 
 it('prints message about flag on forceExit', async () => {
-  const {stderr} = await until(
-    'detect-open-handles',
-    ['outside', '--forceExit'],
-    'Force exiting Jest',
-  );
+  const run = runContinuous('detect-open-handles', ['outside', '--forceExit']);
+  await run.waitUntil(({stderr}) => stderr.includes('Force exiting Jest'));
+  const {stderr} = await run.end();
   const textAfterTest = getTextAfterTest(stderr);
 
   expect(textAfterTest).toMatchSnapshot();
 });
 
 it('prints out info about open handlers', async () => {
-  const {stderr} = await until(
-    'detect-open-handles',
-    ['outside', '--detectOpenHandles'],
-    'Jest has detected',
-  );
+  const run = runContinuous('detect-open-handles', [
+    'outside',
+    '--detectOpenHandles',
+  ]);
+  await run.waitUntil(({stderr}) => stderr.includes('Jest has detected'));
+  const {stderr} = await run.end();
   const textAfterTest = getTextAfterTest(stderr);
 
   expect(textAfterTest).toMatchSnapshot();
@@ -73,11 +76,13 @@ it('does not report promises', () => {
 });
 
 it('prints out info about open handlers from inside tests', async () => {
-  const {stderr} = await until(
-    'detect-open-handles',
-    ['inside', '--detectOpenHandles'],
-    'Jest has detected',
-  );
+  const run = runContinuous('detect-open-handles', [
+    'inside',
+    '--detectOpenHandles',
+  ]);
+  await run.waitUntil(({stderr}) => stderr.includes('Jest has detected'));
+  const {stderr} = await run.end();
+
   const textAfterTest = getTextAfterTest(stderr);
 
   expect(textAfterTest).toMatchSnapshot();

diff --git a/e2e/runJest.js b/e2e/runJest.js
@@ -23,6 +23,8 @@ type RunJestOptions = {
   stripAnsi?: boolean, // remove colors from stdout and stderr
 };
 
+type ConditionFunction = (...Array<any>) => boolean;
+
 // return the result of the spawned process:
 //  [ 'status', 'signal', 'output', 'pid', 'stdout', 'stderr',
 //    'envPairs', 'options', 'args', 'file' ]
@@ -94,11 +96,11 @@ export const json = function(
   return result;
 };
 
-// Runs `jest` until a given output is achieved, then kills it with `SIGTERM`
-export const until = async function(
+// Runs `jest` continously (watch mode) and allows the caller to wait for
+// conditions on stdout and stderr and to end the process.
+export const runContinuous = function(
   dir: string,
   args?: Array<string>,
-  text: string,
   options: RunJestOptions = {},
 ) {
   const isRelative = dir[0] !== '/';
@@ -128,29 +130,67 @@ export const until = async function(
     reject: false,
   });
 
-  jestPromise.stderr.pipe(
-    new Writable({
-      write(chunk, encoding, callback) {
-        const output = chunk.toString('utf8');
+  let stderr = '';
+  let stdout = '';
+  const pending = new Set();
 
-        if (output.includes(text)) {
-          jestPromise.kill();
-        }
+  const dispatch = () => {
+    for (const fn of pending) {
+      fn({stderr, stdout});
+    }
+  };
 
+  jestPromise.stdout.pipe(
+    new Writable({
+      write(chunk, encoding, callback) {
+        stdout += chunk.toString('utf8');
+        dispatch();
         callback();
       },
     }),
   );
 
-  const result = await jestPromise;
-
-  // For compat with cross-spawn
-  result.status = result.code;
-
-  result.stdout = normalizeIcons(result.stdout);
-  if (options.stripAnsi) result.stdout = stripAnsi(result.stdout);
-  result.stderr = normalizeIcons(result.stderr);
-  if (options.stripAnsi) result.stderr = stripAnsi(result.stderr);
+  jestPromise.stderr.pipe(
+    new Writable({
+      write(chunk, encoding, callback) {
+        stderr += chunk.toString('utf8');
+        dispatch();
+        callback();
+      },
+    }),
+  );
 
-  return result;
+  return {
+    async end() {
+      jestPromise.kill();
+
+      const result = await jestPromise;
+
+      // For compat with cross-spawn
+      result.status = result.code;
+
+      result.stdout = normalizeIcons(stdout);
+      if (options.stripAnsi) result.stdout = stripAnsi(result.stdout);
+      result.stderr = normalizeIcons(stderr);
+      if (options.stripAnsi) result.stderr = stripAnsi(result.stderr);
+
+      return result;
+    },
+
+    getCurrentOutput() {
+      return {stderr, stdout};
+    },
+
+    waitUntil(fn: ConditionFunction): Promise<void> {
+      return new Promise(resolve => {
+        const check = state => {
+          if (fn(state)) {
+            pending.delete(check);
+            resolve();
+          }
+        };
+        pending.add(check);
+      });
+    },
+  };
 };