155 lines
		
	
	
		
			4.5 KiB
		
	
	
	
		
			JavaScript
		
	
	
		
			Executable File
		
	
	
	
	
			
		
		
	
	
			155 lines
		
	
	
		
			4.5 KiB
		
	
	
	
		
			JavaScript
		
	
	
		
			Executable File
		
	
	
	
	
/**
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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('../types').Rule.RuleModule} */
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module.exports = {
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	meta: {
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		type: "suggestion",
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		defaultOptions: [
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			{
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				allowEmptyReject: false,
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			},
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		],
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		docs: {
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			description:
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				"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" },
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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:
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				"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 [{ allowEmptyReject }] = context.options;
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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 && allowEmptyReject) {
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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" &&
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					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(
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				node.callee,
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				"Promise",
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				"reject",
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			);
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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" &&
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					node.callee.name === "Promise" &&
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					node.arguments.length &&
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					astUtils.isFunction(node.arguments[0]) &&
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					node.arguments[0].params.length > 1 &&
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					node.arguments[0].params[1].type === "Identifier"
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				) {
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					sourceCode
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						.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(
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							variable =>
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								variable.name ===
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								node.arguments[0].params[1].name,
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						)
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						// Get the references to that variable.
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						.references // 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(
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							ref =>
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								ref.identifier.parent.type ===
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									"CallExpression" &&
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								ref.identifier === ref.identifier.parent.callee,
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						)
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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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