Simplify test suite (#2858)

* first fixtures tests

* fix bad custom handler for already bad CI issue

.gitignore

@@ -7,6 +7,7 @@ lerna-debug.log
 node_modules
 package-lock.json
 create-snowpack-app/*/build
+test/__temp__
 test/build/**/build
 test/build/**/TEST_BUILD_OUT
 test/build/**/web_modules

CONTRIBUTING.md

@@ -64,14 +64,18 @@ From the repository's root folder, run
 ```bash
 yarn build
 yarn test
-yarn test:dev # might fail on windows, see #1171
+yarn test:dev # sometimes flaky on windows, see #1171
 ```
 
 ### Snapshot tests
 
-_Update Dec 2020: we’re working on improving this! Snapshots are now mostly gone from `test/build`, and we’ll be working through `test/esinstall` next. We‘ll wait to finish the work before updating this section, but know that this may become outdated soon._
+_Update March 2021: we’re working on improving this and would love your help converting old test directories to smaller TypeScript tests/fixtures!_
 
-The way our snapshot tests work is they test Snowpack by building the codebases in `test/build`. You'll almost always have a "failed" snapshot test when you make a contribution because your new change will make the final build different. You'll want to take a new snapshot. To do this run:
+All new tests should live in either `test/snowpack`, `test/esinstall`, or the `test` directory of one of our plugins (ex: `plugins/plugin-dotenv/test/plugin.test.js`). `test/build` is considered legacy and is in the process of getting converted into `test/snowpack`.
+
+The way our snapshot tests work is they test Snowpack by building a project. Because Snowpack's build method uses the dev server internally, this is a good way to test the build behavior of both dev & build together.
+
+You'll almost always have a "failed" snapshot test when you make a contribution because your new change will make the final build different. You'll want to take a new snapshot. To do this run:
 
 ```bash
 yarn test -u
@@ -81,10 +85,10 @@ You'll notice this changes the snapshot file. Commit this change and submit it a
 
 ### Filtering tests
 
-You can filter the tests that are being run using Jest's [`--testNamePattern`](https://jestjs.io/docs/en/cli#--testnamepatternregex) (alias: `-t`) CLI option. You can ignore the `123 snapshots obsolete` messages.
+Jest supports basic test filtering to only run a subset of our test suite. The [`--testNamePattern`](https://jestjs.io/docs/en/cli#--testnamepatternregex) flag also works as well.
 
 ```bash
-yarn test --testNamePattern treeshake
+yarn test treeshake
 ```
 
 ## Run local snowpack in another project

jest.config.js

@@ -5,6 +5,6 @@ module.exports = {
     '<rootDir>/test/create-snowpack-app/test-install', // don’t run tests inside our mock create-snowpack-app install
     '<rootDir>/www', // docs has its own tests
   ],
-  setupFilesAfterEnv: ['<rootDir>/jest.setup.js'],
+  globalSetup: '<rootDir>/jest.setup.js',
   testEnvironment: 'node',
 };

jest.setup.js

@@ -1 +1,10 @@
-process.env.NO_COLOR = true; // enable NO_COLOR mode for Jest
+module.exports = async () => {
+    // enable NO_COLOR mode for Jest
+    process.env.NO_COLOR = true; 
+    // Clear the temp directory
+    const path = require('path');
+    const rimraf = require('rimraf');
+    const fs = require('fs');
+    rimraf.sync(path.join(__dirname, 'test', '__temp__'));
+    fs.mkdirSync(path.join(__dirname, 'test', '__temp__'));
+};

snowpack/src/config.ts

@@ -379,7 +379,7 @@ function normalizeMount(config: SnowpackConfig) {
   }
   // if no mounted directories, mount the root directory to the base URL
   if (!Object.keys(normalizedMount).length) {
-    normalizedMount[process.cwd()] = {
+    normalizedMount[config.root] = {
       url: '/',
       static: false,
       resolve: true,

snowpack/src/util.ts

@@ -72,7 +72,16 @@ export function deleteFromBuildSafe(dir: string, config: SnowpackConfig) {
 
 /** Read file from disk; return a string if it’s a code file */
 export async function readFile(filepath: string): Promise<string | Buffer> {
-  const data = await fs.promises.readFile(filepath);
+  let data = await fs.promises.readFile(filepath);
+  if (!data) {
+    console.error(
+      `Unexpected Node.js error: readFile(${filepath}) returned undefined.\n\n` +
+        `Somehow in Github CI / Jest its possible for fs.promises.readFile to return undefined.\n` +
+        `This should be impossible, and has not yet been reproduced in the real world, but we do see it in our own CI.\n` +
+        `If you are seeing this error, please report!`,
+    );
+    data = fs.readFileSync(filepath);
+  }
   const isBinary = await isBinaryFile(data);
   return isBinary ? data : data.toString('utf8');
 }