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fix(hoist-plugin): hoist pure constants to support experimental JSX transform in mocks #10723

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Nov 1, 2020
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1 change: 1 addition & 0 deletions CHANGELOG.md
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
### Fixes

- `[babel-plugin-jest-hoist]` Preserve order of hoisted mock nodes within containing block ([#10536](https://github.com/facebook/jest/pull/10536))
- `[babel-plugin-jest-hoist]` Hoist pure constants to support experimental JSX transform in hoisted mocks ([#10723](https://github.com/facebook/jest/pull/10723))
- `[babel-preset-jest]` Update `babel-preset-current-node-syntax` to support top level await ([#10747](https://github.com/facebook/jest/pull/10747))
- `[expect]` Stop modifying the sample in `expect.objectContaining()` ([#10711](https://github.com/facebook/jest/pull/10711))
- `[jest-circus, jest-jasmine2]` fix: don't assume `stack` is always a string ([#10697](https://github.com/facebook/jest/pull/10697))
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5 changes: 4 additions & 1 deletion packages/babel-plugin-jest-hoist/package.json
Original file line number Diff line number Diff line change
Expand Up @@ -20,9 +20,12 @@
},
"devDependencies": {
"@babel/core": "^7.11.6",
"@babel/preset-react": "^7.12.1",
"@types/babel__template": "^7.0.2",
"@types/node": "*",
"babel-plugin-tester": "^10.0.0"
"@types/prettier": "^2.0.0",
"babel-plugin-tester": "^10.0.0",
"prettier": "^2.1.1"
},
"publishConfig": {
"access": "public"
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Original file line number Diff line number Diff line change
@@ -1,5 +1,43 @@
// Jest Snapshot v1, https://goo.gl/fbAQLP

exports[`babel-plugin-jest-hoist automatic react runtime: automatic react runtime 1`] = `

jest.mock('./App', () => () => <div>Hello world</div>);

↓ ↓ ↓ ↓ ↓ ↓

var _jsxFileName = "/root/project/src/file.js";

_getJestObj().mock("./App", () => () =>
/*#__PURE__*/ _jsxDEV(
"div",
{
children: "Hello world"
},
void 0,
false,
{
fileName: _jsxFileName,
lineNumber: 1,
columnNumber: 32
},
this
)
);

import { jsxDEV as _jsxDEV } from "react/jsx-dev-runtime";

function _getJestObj() {
const { jest } = require("@jest/globals");

_getJestObj = () => jest;

return jest;
}


`;

exports[`babel-plugin-jest-hoist top level mocking: top level mocking 1`] = `

require('x');
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28 changes: 28 additions & 0 deletions packages/babel-plugin-jest-hoist/src/__tests__/hoistPlugin.test.ts
Original file line number Diff line number Diff line change
Expand Up @@ -6,13 +6,41 @@
*
*/

import * as path from 'path';
import pluginTester from 'babel-plugin-tester';
import {format as formatCode} from 'prettier';
import babelPluginJestHoist from '..';

pluginTester({
plugin: babelPluginJestHoist,
pluginName: 'babel-plugin-jest-hoist',
tests: {
'automatic react runtime': {
babelOptions: {
babelrc: false,
configFile: false,
filename: path.resolve(__dirname, '../file.js'),
presets: [
[
require.resolve('@babel/preset-react'),
{development: true, runtime: 'automatic'},
],
],
},
code: `
jest.mock('./App', () => () => <div>Hello world</div>);
`,
formatResult(code) {
// replace the filename with something that will be the same across OSes and machine
const codeWithoutSystemPath = code.replace(
/var _jsxFileName = ".*";/,
'var _jsxFileName = "/root/project/src/file.js";',
);

return formatCode(codeWithoutSystemPath, {parser: 'babel'});
},
snapshot: true,
},
'top level mocking': {
code: `
require('x');
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59 changes: 48 additions & 11 deletions packages/babel-plugin-jest-hoist/src/index.ts
Original file line number Diff line number Diff line change
Expand Up @@ -16,15 +16,20 @@ import {
Identifier,
Node,
Program,
VariableDeclaration,
VariableDeclarator,
callExpression,
emptyStatement,
isIdentifier,
variableDeclaration,
} from '@babel/types';

const JEST_GLOBAL_NAME = 'jest';
const JEST_GLOBALS_MODULE_NAME = '@jest/globals';
const JEST_GLOBALS_MODULE_JEST_EXPORT_NAME = 'jest';

const hoistedVariables = new WeakSet<VariableDeclarator>();

// We allow `jest`, `expect`, `require`, all default Node.js globals and all
// ES2015 built-ins to be used inside of a `jest.mock` factory.
// We also allow variables prefixed with `mock` as an escape-hatch.
Expand Down Expand Up @@ -133,12 +138,26 @@ FUNCTIONS.mock = args => {
}

if (!found) {
SimenB marked this conversation as resolved.
Show resolved Hide resolved
const isAllowedIdentifier =
let isAllowedIdentifier =
(scope.hasGlobal(name) && ALLOWED_IDENTIFIERS.has(name)) ||
/^mock/i.test(name) ||
// Allow istanbul's coverage variable to pass.
/^(?:__)?cov/.test(name);

if (!isAllowedIdentifier) {
const binding = scope.bindings[name];

if (binding?.path.isVariableDeclarator()) {
const {node} = binding.path;
const initNode = node.init;

if (initNode && binding.constant && scope.isPure(initNode, true)) {
hoistedVariables.add(node);
isAllowedIdentifier = true;
}
}
}

if (!isAllowedIdentifier) {
throw id.buildCodeFrameError(
'The module factory of `jest.mock()` is not allowed to ' +
Expand Down Expand Up @@ -273,7 +292,7 @@ export default (): PluginObj<{
visitor: {
ExpressionStatement(exprStmt) {
const jestObjExpr = extractJestObjExprIfHoistable(
exprStmt.get<'expression'>('expression'),
exprStmt.get('expression'),
);
if (jestObjExpr) {
jestObjExpr.replaceWith(
Expand All @@ -285,24 +304,25 @@ export default (): PluginObj<{
// in `post` to make sure we come after an import transform and can unshift above the `require`s
post({path: program}) {
const self = this;

visitBlock(program);
program.traverse({
BlockStatement: visitBlock,
});
program.traverse({BlockStatement: visitBlock});

function visitBlock(block: NodePath<BlockStatement> | NodePath<Program>) {
// use a temporary empty statement instead of the real first statement, which may itself be hoisted
const [firstNonHoistedStatementOfBlock] = block.unshiftContainer(
'body',
const [varsHoistPoint, callsHoistPoint] = block.unshiftContainer('body', [
emptyStatement(),
);
emptyStatement(),
]);
block.traverse({
CallExpression: visitCallExpr,
VariableDeclarator: visitVariableDeclarator,
// do not traverse into nested blocks, or we'll hoist calls in there out to this block
// @ts-expect-error blacklist is not known
blacklist: ['BlockStatement'],
});
firstNonHoistedStatementOfBlock.remove();
callsHoistPoint.remove();
varsHoistPoint.remove();

function visitCallExpr(callExpr: NodePath<CallExpression>) {
const {
Expand All @@ -315,15 +335,32 @@ export default (): PluginObj<{
const mockStmt = callExpr.getStatementParent();

if (mockStmt) {
const mockStmtNode = mockStmt.node;
const mockStmtParent = mockStmt.parentPath;
if (mockStmtParent.isBlock()) {
const mockStmtNode = mockStmt.node;
mockStmt.remove();
firstNonHoistedStatementOfBlock.insertBefore(mockStmtNode);
callsHoistPoint.insertBefore(mockStmtNode);
}
}
}
}

function visitVariableDeclarator(varDecl: NodePath<VariableDeclarator>) {
if (hoistedVariables.has(varDecl.node)) {
// should be assert function, but it's not. So let's cast below
varDecl.parentPath.assertVariableDeclaration();

const {kind, declarations} = varDecl.parent as VariableDeclaration;
if (declarations.length === 1) {
varDecl.parentPath.remove();
} else {
varDecl.remove();
}
varsHoistPoint.insertBefore(
variableDeclaration(kind, [varDecl.node]),
);
}
}
}
},
});
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5 changes: 4 additions & 1 deletion yarn.lock
Original file line number Diff line number Diff line change
Expand Up @@ -1456,7 +1456,7 @@ __metadata:
languageName: node
linkType: hard

"@babel/preset-react@npm:*, @babel/preset-react@npm:^7.0.0, @babel/preset-react@npm:^7.9.4":
"@babel/preset-react@npm:*, @babel/preset-react@npm:^7.0.0, @babel/preset-react@npm:^7.12.1, @babel/preset-react@npm:^7.9.4":
version: 7.12.1
resolution: "@babel/preset-react@npm:7.12.1"
dependencies:
Expand Down Expand Up @@ -4830,13 +4830,16 @@ __metadata:
resolution: "babel-plugin-jest-hoist@workspace:packages/babel-plugin-jest-hoist"
dependencies:
"@babel/core": ^7.11.6
"@babel/preset-react": ^7.12.1
"@babel/template": ^7.3.3
"@babel/types": ^7.3.3
"@types/babel__core": ^7.0.0
"@types/babel__template": ^7.0.2
"@types/babel__traverse": ^7.0.6
"@types/node": "*"
"@types/prettier": ^2.0.0
babel-plugin-tester: ^10.0.0
prettier: ^2.1.1
languageName: unknown
linkType: soft

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