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Make React tests fast #2187

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32 changes: 9 additions & 23 deletions fb-www/README.md
Original file line number Diff line number Diff line change
Expand Up @@ -81,46 +81,32 @@ To enter a watching mode, run `yarn test-react --watch`. This will re-run them o

If you’re debugging a specific test case, the easiest way to focus on it is to:

* Open `scripts/test-react.js`.
* Open `test/react/SomeTestFileName-test.js`.
* Find the test in the code by searching for its filename.

For example, you may find something like:

```js
it("fb-www 5", async () => {
await runTest(directory, "fb5.js");
it("fb-www 5", () => {
runTest(directory, "fb5.js");
});
```

* Change `it` to `fit` to “focus” on a specific test and skip all other tests.

```diff
- it("fb-www 5", async () => {
+ fit("fb-www 5", async () => {
await runTest(directory, "fb5.js");
- it("fb-www 5", () => {
+ fit("fb-www 5", () => {
runTest(directory, "fb5.js");
});
```
* Run the watch mode: `yarn test-react --watch`
* Run the watch mode: `yarn test-react --watch SomeTestFileName`

Now only this test alone will re-run on every change which should help debug problems faster.

By default, tests run in four different input/output configurations. If too many runs are confusing when debugging a problem, you can comment out all modes except one [at the very bottom of the test file](https://github.com/facebook/prepack/blob/30876d5becade1dad7319682a075b6df252341a2/scripts/test-react.js#L748-L753).
By default, tests run in four different input/output configurations. If too many runs are confusing when debugging a problem, you can run a subset with `yarn test-react-fast --watch SomeFileName`. Unlike `yarn test-react`, `yarn test-react-fast` skips checking that JSX syntax works. This mode is much faster but you will see some annoying messages about obsolete snapshots (which you should ignore in this mode).

For example:

```diff
// pre non-transpiled
runTestSuite(true, false);
-runTestSuite(false, false);
+// runTestSuite(false, false);
// pre transpiled
-runTestSuite(true, true);
+ // runTestSuite(true, true);
-runTestSuite(false, true);
+ // runTestSuite(false, true);
```

Finally, sometimes it’s helpful to see the code Prepack is emitting. Search for a [variable called `transformedSource`](https://github.com/facebook/prepack/blob/30876d5becade1dad7319682a075b6df252341a2/scripts/test-react.js#L115) in the test file.
Finally, sometimes it’s helpful to see the code Prepack is emitting. Search for a variable called `transformedSource` a file called `setupReactTests.js`.
If you add `console.log(transformedSource)` you will see the Prepack output during test runs.

Don’t forget to revert any such changes before committing!
Expand Down
11 changes: 8 additions & 3 deletions package.json
Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,8 @@
"test-error-handler-with-coverage": "./node_modules/.bin/istanbul cover ./lib/test-error-handler.js --dir coverage.error && ./node_modules/.bin/remap-istanbul -i coverage.error/coverage.json -o coverage-sourcemapped.error -t html",
"test-node-cli-mode": "bash < scripts/test-node-cli-mode.sh",
"test-std-in": "bash < scripts/test-std-in.sh",
"test-react": "jest scripts/test-react",
"test-react": "jest",
"test-react-fast": "SKIP_REACT_JSX_TESTS=true jest",
"test": "yarn test-residual && yarn test-serializer && yarn test-sourcemaps && yarn test-error-handler && yarn test-std-in && yarn test-test262 && yarn test-internal && yarn test-internal-react && yarn test-react",
"test-coverage-most": "./node_modules/.bin/istanbul --stack_size=10000 --max_old_space_size=16384 cover ./lib/multi-runner.js --dir coverage.most && ./node_modules/.bin/remap-istanbul -i coverage.most/coverage.json -o coverage-sourcemapped -t html",
"test-all-coverage": "./node_modules/.bin/istanbul --stack_size=10000 --max_old_space_size=16384 cover ./lib/multi-runner.js --dir coverage.most && ./node_modules/.bin/istanbul --stack_size=10000 --max_old_space_size=16384 cover ./lib/test262-runner.js --timeout 50 --singleThreaded && ./node_modules/.bin/remap-istanbul -i coverage/coverage.json -i coverage.most/coverage.json -o coverage-sourcemapped -t html",
Expand Down Expand Up @@ -97,7 +98,7 @@
"graceful-fs": "^4.1.11",
"invariant": "^2.2.0",
"istanbul": "^0.4.5",
"jest": "^22.2.1",
"jest": "^23.2.0",
"js-yaml": "^3.6.1",
"jsdom": "^9.2.1",
"madge": "^1.6.0",
Expand Down Expand Up @@ -126,8 +127,12 @@
"license": "BSD-3-Clause",
"author": "Facebook",
"jest": {
"roots": [
"<rootDir>/lib/",
"<rootDir>/test/react/"
],
"testMatch": [
"**/scripts/test-react.js"
"**/test/react/*-test.js"
]
}
}
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