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Hoist static variables before hoisted mocks #653

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merged 1 commit into from Nov 1, 2020
Merged

Hoist static variables before hoisted mocks #653

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9 changes: 3 additions & 6 deletions packages/babel-plugin-jest-hoist/src/__tests__/__snapshots__/hoistPlugin.test.ts.snap
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Expand Up @@ -6,6 +6,8 @@ jest.mock('./App', () => () => <div>Hello world</div>);

↓ ↓ ↓ ↓ ↓ ↓

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

_getJestObj().mock("./App", () => () =>
/*#__PURE__*/ _jsxDEV(
"div",
Expand All @@ -15,7 +17,7 @@ _getJestObj().mock("./App", () => () =>
void 0,
false,
{
fileName: _hoistedMockFactoryVariable(),
fileName: _jsxFileName,
lineNumber: 1,
columnNumber: 32
},
Expand All @@ -24,7 +26,6 @@ _getJestObj().mock("./App", () => () =>
);

import { jsxDEV as _jsxDEV } from "react/jsx-dev-runtime";
var _jsxFileName = "/root/project/src/file.js";

function _getJestObj() {
const { jest } = require("@jest/globals");
Expand All @@ -34,10 +35,6 @@ function _getJestObj() {
return jest;
}

function _hoistedMockFactoryVariable() {
return "/root/project/src/file.js";
}


`;

Expand Down
53 changes: 28 additions & 25 deletions packages/babel-plugin-jest-hoist/src/index.ts
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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 @@ -146,20 +151,7 @@ FUNCTIONS.mock = args => {
const initNode = binding.path.node.init;

if (initNode && binding.constant && scope.isPure(initNode, true)) {
const identifier = scope.generateUidIdentifier(
'hoistedMockFactoryVariable',
);

binding.path.parentPath.insertAfter(
createHoistedVariable({
HOISTED_NAME: identifier,
HOISTED_VALUE: binding.path.node.init,
}),
);

// replace reference with a call to the new function
id.replaceWith(callExpression(identifier, []));

hoistedVariables.add(binding.path.node);
isAllowedIdentifier = true;
}
}
Expand Down Expand Up @@ -202,12 +194,6 @@ function GETTER_NAME() {
}
`;

const createHoistedVariable = statement`
function HOISTED_NAME() {
return HOISTED_VALUE;
}
`;

const isJestObject = (expression: NodePath<Expression>): boolean => {
// global
if (
Expand Down Expand Up @@ -317,24 +303,27 @@ 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,
});

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 @@ -351,11 +340,25 @@ export default (): PluginObj<{
const mockStmtParent = mockStmt.parentPath;
if (mockStmtParent.isBlock()) {
mockStmt.remove();
firstNonHoistedStatementOfBlock.insertBefore(mockStmtNode);
callsHoistPoint.insertBefore(mockStmtNode);
}
}
}
}

function visitVariableDeclarator(varDecl: NodePath<VariableDeclarator>) {
if (hoistedVariables.has(varDecl.node)) {
const {kind, declarations} = varDecl.parent as VariableDeclaration;
if (declarations.length === 1) {
varDecl.parentPath.remove();
} else {
varDecl.remove();
}
varsHoistPoint.insertBefore(
variableDeclaration(kind, [varDecl.node]),
);
}
}
}
},
});
Expand Down