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132 lines
5.4 KiB
132 lines
5.4 KiB
/**
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* @fileoverview restrict values that can be used as Promise rejection reasons
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* @author Teddy Katz
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*/
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"use strict";
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const astUtils = require("./utils/ast-utils");
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//------------------------------------------------------------------------------
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// Rule Definition
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//------------------------------------------------------------------------------
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/** @type {import('../shared/types').Rule} */
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module.exports = {
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meta: {
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type: "suggestion",
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docs: {
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description: "Require using Error objects as Promise rejection reasons",
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recommended: false,
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url: "https://eslint.org/docs/latest/rules/prefer-promise-reject-errors"
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},
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fixable: null,
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schema: [
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{
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type: "object",
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properties: {
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allowEmptyReject: { type: "boolean", default: false }
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},
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additionalProperties: false
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}
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],
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messages: {
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rejectAnError: "Expected the Promise rejection reason to be an Error."
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}
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},
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create(context) {
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const ALLOW_EMPTY_REJECT = context.options.length && context.options[0].allowEmptyReject;
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const sourceCode = context.sourceCode;
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//----------------------------------------------------------------------
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// Helpers
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//----------------------------------------------------------------------
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/**
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* Checks the argument of a reject() or Promise.reject() CallExpression, and reports it if it can't be an Error
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* @param {ASTNode} callExpression A CallExpression node which is used to reject a Promise
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* @returns {void}
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*/
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function checkRejectCall(callExpression) {
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if (!callExpression.arguments.length && ALLOW_EMPTY_REJECT) {
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return;
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}
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if (
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!callExpression.arguments.length ||
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!astUtils.couldBeError(callExpression.arguments[0]) ||
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callExpression.arguments[0].type === "Identifier" && callExpression.arguments[0].name === "undefined"
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) {
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context.report({
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node: callExpression,
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messageId: "rejectAnError"
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});
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}
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}
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/**
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* Determines whether a function call is a Promise.reject() call
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* @param {ASTNode} node A CallExpression node
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* @returns {boolean} `true` if the call is a Promise.reject() call
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*/
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function isPromiseRejectCall(node) {
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return astUtils.isSpecificMemberAccess(node.callee, "Promise", "reject");
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}
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//----------------------------------------------------------------------
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// Public
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//----------------------------------------------------------------------
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return {
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// Check `Promise.reject(value)` calls.
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CallExpression(node) {
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if (isPromiseRejectCall(node)) {
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checkRejectCall(node);
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}
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},
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/*
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* Check for `new Promise((resolve, reject) => {})`, and check for reject() calls.
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* This function is run on "NewExpression:exit" instead of "NewExpression" to ensure that
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* the nodes in the expression already have the `parent` property.
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*/
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"NewExpression:exit"(node) {
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if (
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node.callee.type === "Identifier" && node.callee.name === "Promise" &&
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node.arguments.length && astUtils.isFunction(node.arguments[0]) &&
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node.arguments[0].params.length > 1 && node.arguments[0].params[1].type === "Identifier"
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) {
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sourceCode.getDeclaredVariables(node.arguments[0])
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/*
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* Find the first variable that matches the second parameter's name.
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* If the first parameter has the same name as the second parameter, then the variable will actually
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* be "declared" when the first parameter is evaluated, but then it will be immediately overwritten
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* by the second parameter. It's not possible for an expression with the variable to be evaluated before
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* the variable is overwritten, because functions with duplicate parameters cannot have destructuring or
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* default assignments in their parameter lists. Therefore, it's not necessary to explicitly account for
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* this case.
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*/
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.find(variable => variable.name === node.arguments[0].params[1].name)
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// Get the references to that variable.
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.references
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// Only check the references that read the parameter's value.
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.filter(ref => ref.isRead())
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// Only check the references that are used as the callee in a function call, e.g. `reject(foo)`.
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.filter(ref => ref.identifier.parent.type === "CallExpression" && ref.identifier === ref.identifier.parent.callee)
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// Check the argument of the function call to determine whether it's an Error.
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.forEach(ref => checkRejectCall(ref.identifier.parent));
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}
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}
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};
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}
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};
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