688 lines
20 KiB
JavaScript
688 lines
20 KiB
JavaScript
/**
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* @fileoverview Rule to preserve caught errors when re-throwing exceptions
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* @author Amnish Singh Arora
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*/
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"use strict";
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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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const astUtils = require("./utils/ast-utils");
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//------------------------------------------------------------------------------
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// Types
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//------------------------------------------------------------------------------
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/** @typedef {import("estree").Node} ASTNode */
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/** @typedef {import("eslint").Rule.Fix} Fix */
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/** @typedef {import("eslint").Rule.RuleFixer} RuleFixer */
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//------------------------------------------------------------------------------
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// Helpers
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//------------------------------------------------------------------------------
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/*
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* This is an indicator of an error cause node, that is too complicated to be detected and fixed.
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* Eg, when error options is an `Identifier` or a `SpreadElement`.
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*/
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const UNKNOWN_CAUSE = Symbol("unknown_cause");
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const BUILT_IN_ERROR_TYPES = new Set([
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"Error",
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"EvalError",
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"RangeError",
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"ReferenceError",
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"SyntaxError",
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"TypeError",
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"URIError",
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"AggregateError",
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]);
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/**
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* Finds and returns information about the `cause` property of an error being thrown.
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* @param {ASTNode} throwStatement `ThrowStatement` to be checked.
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* @param {number} optionsIndex The index of the options argument in the error constructor.
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* @returns {{ value: ASTNode; multipleDefinitions: boolean; } | UNKNOWN_CAUSE | null}
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* Information about the `cause` of the error being thrown, such as the value node and
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* whether there are multiple definitions of `cause`. `null` if there is no `cause`.
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*/
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function getErrorCause(throwStatement, optionsIndex) {
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const throwExpression = throwStatement.argument;
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/*
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* Make sure there is no `SpreadElement` at or before the `optionsIndex`
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* as this messes up the effective order of arguments and makes it complicated
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* to track where the actual error options need to be at
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*/
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const spreadExpressionIndex = throwExpression.arguments.findIndex(
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arg => arg.type === "SpreadElement",
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);
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if (spreadExpressionIndex >= 0 && spreadExpressionIndex <= optionsIndex) {
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return UNKNOWN_CAUSE;
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}
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const errorOptions = throwExpression.arguments[optionsIndex];
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if (errorOptions) {
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if (errorOptions.type === "ObjectExpression") {
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if (
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errorOptions.properties.some(
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prop => prop.type === "SpreadElement",
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)
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) {
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/*
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* If there is a spread element as part of error options, it is too complicated
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* to verify if the cause is used properly and auto-fix.
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*/
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return UNKNOWN_CAUSE;
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}
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const causeProperties = errorOptions.properties.filter(
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prop => astUtils.getStaticPropertyName(prop) === "cause",
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);
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const causeProperty = causeProperties.at(-1);
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return causeProperty
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? {
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value: causeProperty.value,
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multipleDefinitions: causeProperties.length > 1,
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}
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: null;
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}
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// Error options exist, but too complicated to be analyzed/fixed
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return UNKNOWN_CAUSE;
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}
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return null;
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}
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/**
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* Finds and returns the `CatchClause` node, that the `node` is part of.
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* @param {ASTNode} node The AST node to be evaluated.
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* @returns {ASTNode | null } The closest parent `CatchClause` node, `null` if the `node` is not in a catch block.
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*/
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function findParentCatch(node) {
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let currentNode = node;
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while (currentNode && currentNode.type !== "CatchClause") {
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if (
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[
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"FunctionDeclaration",
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"FunctionExpression",
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"ArrowFunctionExpression",
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"StaticBlock",
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].includes(currentNode.type)
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) {
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/*
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* Make sure the ThrowStatement is not made inside a function definition or a static block inside a high level catch.
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* In such cases, the caught error is not directly related to the Throw.
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*
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* For example,
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* try {
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* } catch (error) {
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* foo = {
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* bar() {
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* throw new Error();
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* }
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* };
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* }
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*/
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return null;
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}
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currentNode = currentNode.parent;
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}
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return currentNode;
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}
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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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requireCatchParameter: false,
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errorClassNames: [],
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},
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],
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docs: {
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description:
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"Disallow losing originally caught error when re-throwing custom errors",
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recommended: true,
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url: "https://eslint.org/docs/latest/rules/preserve-caught-error", // URL to the documentation page for this rule
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},
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schema: [
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{
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type: "object",
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properties: {
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requireCatchParameter: {
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type: "boolean",
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description:
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"Requires the catch blocks to always have the caught error parameter so it is not discarded.",
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},
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errorClassNames: {
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type: "array",
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description:
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"Additional error class names to check for cause preservation.",
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items: {
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oneOf: [
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{
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type: "string",
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},
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{
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type: "object",
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required: ["name", "argumentPosition"],
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properties: {
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name: {
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type: "string",
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},
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argumentPosition: {
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type: "integer",
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minimum: 1,
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},
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},
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additionalProperties: false,
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},
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],
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},
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uniqueItems: true,
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},
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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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missingCause:
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"There is no `cause` attached to the symptom error being thrown.",
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incorrectCause:
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"The symptom error is being thrown with an incorrect `cause`.",
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includeCause:
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"Include the original caught error as the `cause` of the symptom error.",
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missingCatchErrorParam:
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"The caught error is not accessible because the catch clause lacks the error parameter. Start referencing the caught error using the catch parameter.",
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partiallyLostError:
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"Re-throws cannot preserve the caught error as a part of it is being lost due to destructuring.",
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caughtErrorShadowed:
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"The caught error is being attached as `cause`, but is shadowed by a closer scoped redeclaration.",
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},
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hasSuggestions: true,
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},
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create(context) {
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const sourceCode = context.sourceCode;
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const [{ requireCatchParameter, errorClassNames }] = context.options;
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const errorClassNamesMap = new Map();
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for (const item of errorClassNames) {
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const name = typeof item === "string" ? item : item.name;
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const argumentPosition =
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typeof item === "string" ? 2 : item.argumentPosition;
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errorClassNamesMap.set(name, argumentPosition);
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}
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//----------------------------------------------------------------------
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// Helpers
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//----------------------------------------------------------------------
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/**
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* Checks if the given callee refers to a built-in global Error constructor.
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* @param {ASTNode} callee The callee node.
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* @returns {boolean} `true` if the callee is a built-in global Error constructor.
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*/
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function isBuiltInGlobalError(callee) {
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return (
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callee.type === "Identifier" &&
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BUILT_IN_ERROR_TYPES.has(callee.name) &&
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sourceCode.isGlobalReference(callee)
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);
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}
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/**
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* Checks if a `ThrowStatement` is constructing and throwing a new `Error` object.
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*
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* Covers all the error types on `globalThis` that support `cause` property:
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* https://github.com/microsoft/TypeScript/blob/main/src/lib/es2022.error.d.ts
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* @param {ASTNode} throwStatement The `ThrowStatement` that needs to be checked.
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* @returns {boolean} `true` if a new "Error" is being thrown, else `false`.
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*/
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function isThrowingNewError(throwStatement) {
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if (!(
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throwStatement.argument.type === "NewExpression" ||
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throwStatement.argument.type === "CallExpression"
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)) {
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return false;
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}
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const callee = throwStatement.argument.callee;
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/*
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* Make sure the thrown Error instance is one of the built-in global error types.
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* Custom imports could shadow this, which would lead to false positives.
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* e.g. import { Error } from "./my-custom-error.js";
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* throw Error("Failed to perform error prone operations");
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*/
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if (isBuiltInGlobalError(callee)) {
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return true;
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}
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const target =
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callee.type === "MemberExpression" && !callee.computed
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? callee.property
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: callee;
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return (
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target.type === "Identifier" &&
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errorClassNamesMap.has(target.name)
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);
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}
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/**
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* Inserts `cause: <caughtErrorName>` into an inline options object expression.
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* @param {RuleFixer} fixer The fixer object.
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* @param {ASTNode} optionsNode The options object node.
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* @param {string} caughtErrorName The name of the caught error (e.g., "err").
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* @returns {Fix} The fix object.
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*/
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function insertCauseIntoOptions(fixer, optionsNode, caughtErrorName) {
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const properties = optionsNode.properties;
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if (properties.length === 0) {
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// Insert inside empty braces: `{}` → `{ cause: err }`
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return fixer.insertTextAfter(
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sourceCode.getFirstToken(optionsNode),
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`cause: ${caughtErrorName}`,
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);
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}
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const lastProp = properties.at(-1);
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return fixer.insertTextAfter(
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lastProp,
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`, cause: ${caughtErrorName}`,
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);
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}
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/**
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* Finds the first token that isn't followed by a closing parenthesis in a specified range.
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* This is the token after which new arguments should be inserted.
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* @param {Token} firstToken The first token to start searching from.
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* @param {Token} lastToken The last token to scan up to (inclusive).
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* @returns {Token} The first token that isn't followed by a closing parenthesis, or `lastToken` if none is found.
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*/
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function findInsertionTokenAfterParens(firstToken, lastToken) {
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const lastIndex = lastToken.range[1];
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let token = firstToken;
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let nextToken = sourceCode.getTokenAfter(token);
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while (
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nextToken.range[1] <= lastIndex &&
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astUtils.isClosingParenToken(nextToken)
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) {
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token = nextToken;
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nextToken = sourceCode.getTokenAfter(token);
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}
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return token;
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}
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/**
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* Adds arguments for a call/new expression with no arguments.
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* Works for `new Error`, `new (Error)`, and forms that already include empty argument parentheses.
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* @param {RuleFixer} fixer The fixer instance.
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* @param {ASTNode & { callee: ASTNode }} throwExpression The thrown CallExpression or NewExpression node.
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* @param {string} text The arguments to insert.
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* @returns {Fix} The fixer operation.
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*/
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function addArgumentsToEmptyCall(fixer, throwExpression, text) {
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const callClosingParenToken =
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sourceCode.getLastToken(throwExpression);
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const lastCalleeToken = sourceCode.getLastToken(
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throwExpression.callee,
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);
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const parenToken = sourceCode.getFirstTokenBetween(
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lastCalleeToken,
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callClosingParenToken,
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astUtils.isOpeningParenToken,
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);
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if (parenToken) {
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return fixer.insertTextAfter(parenToken, text);
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}
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const insertionToken = findInsertionTokenAfterParens(
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lastCalleeToken,
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callClosingParenToken,
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);
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return fixer.insertTextAfter(insertionToken, `(${text})`);
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}
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/**
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* Appends additional arguments after the last argument of a call/new expression,
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* accounting for any wrapping parentheses around that argument.
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* @param {RuleFixer} fixer The fixer instance.
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* @param {ASTNode & { arguments: ASTNode[] }} throwExpression The thrown CallExpression or NewExpression node.
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* @param {string} text The additional arguments to insert, including the leading comma.
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* @returns {Fix} The fixer operation.
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*/
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function appendArguments(fixer, throwExpression, text) {
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const lastArgument = throwExpression.arguments.at(-1);
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const lastArgumentToken = sourceCode.getLastToken(lastArgument);
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const lastTokenBeforeArgListParen = sourceCode.getLastToken(
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throwExpression,
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{ skip: 1 },
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);
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const insertionToken = findInsertionTokenAfterParens(
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lastArgumentToken,
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lastTokenBeforeArgListParen,
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);
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return fixer.insertTextAfter(insertionToken, text);
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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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ThrowStatement(node) {
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// Check if the throw is inside a catch block
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const parentCatch = findParentCatch(node);
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const throwStatement = node;
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// Check if a new error is being thrown in a catch block
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if (parentCatch && isThrowingNewError(throwStatement)) {
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if (
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parentCatch.param &&
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parentCatch.param.type !== "Identifier"
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) {
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/*
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* When a part of the caught error is being lost at the parameter level, commonly due to destructuring.
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* e.g. catch({ message, ...rest })
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*/
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context.report({
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messageId: "partiallyLostError",
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node: parentCatch,
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});
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return;
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}
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const caughtError =
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parentCatch.param?.type === "Identifier"
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? parentCatch.param
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: null;
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// Check if there are throw statements and caught error is being ignored
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if (!caughtError) {
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if (requireCatchParameter) {
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context.report({
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node: throwStatement,
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messageId: "missingCatchErrorParam",
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});
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return;
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}
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return;
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}
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// Determine the options argument index
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const callee = throwStatement.argument.callee;
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const errorClassName =
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callee.type === "Identifier"
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? callee.name
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: callee.property.name;
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const builtInGlobalError = isBuiltInGlobalError(callee);
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let optionsIndex;
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if (builtInGlobalError) {
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optionsIndex =
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errorClassName === "AggregateError" ? 2 : 1;
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} else {
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const argumentPosition =
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errorClassNamesMap.get(errorClassName);
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optionsIndex = argumentPosition - 1;
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}
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// Check if there is a cause attached to the new error
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const errorCauseInfo = getErrorCause(
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throwStatement,
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optionsIndex,
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);
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if (errorCauseInfo === UNKNOWN_CAUSE) {
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// Error options exist, but too complicated to be analyzed/fixed
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return;
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}
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if (errorCauseInfo === null) {
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// If there is no `cause` attached to the error being thrown.
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context.report({
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messageId: "missingCause",
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node: throwStatement,
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suggest: [
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{
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messageId: "includeCause",
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fix(fixer) {
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const throwExpression =
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throwStatement.argument;
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const args = throwExpression.arguments;
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/**
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* Inserts `cause` into the options argument if it is an `ObjectExpression`.
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* @param {ASTNode} optionsArg The options argument node.
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* @returns {Fix | null} The fix, or `null` if the argument is not an object.
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*/
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function fixExistingOptions(
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optionsArg,
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) {
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if (
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optionsArg.type ===
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"ObjectExpression"
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) {
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return insertCauseIntoOptions(
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fixer,
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optionsArg,
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caughtError.name,
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);
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}
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return null;
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}
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// AggregateError: errors, message, options
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if (
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builtInGlobalError &&
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errorClassName === "AggregateError"
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) {
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const errorsArg = args[0];
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const messageArg = args[1];
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const optionsArg = args[2];
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if (!errorsArg) {
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// Case: `throw new AggregateError()` → insert all arguments
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return addArgumentsToEmptyCall(
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fixer,
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throwExpression,
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`[], "", { cause: ${caughtError.name} }`,
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);
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}
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if (!messageArg) {
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// Case: `throw new AggregateError([])` → insert message and options
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return appendArguments(
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fixer,
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throwExpression,
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`, "", { cause: ${caughtError.name} }`,
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);
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}
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if (!optionsArg) {
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// Case: `throw new AggregateError([], "")` → insert error options only
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return appendArguments(
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fixer,
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throwExpression,
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`, { cause: ${caughtError.name} }`,
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);
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}
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return fixExistingOptions(
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optionsArg,
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);
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}
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// Normal Error types
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if (builtInGlobalError) {
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const messageArg = args[0];
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const optionsArg = args[1];
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if (!messageArg) {
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// Case: `throw new Error()` → insert both message and options
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return addArgumentsToEmptyCall(
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fixer,
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throwExpression,
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`"", { cause: ${caughtError.name} }`,
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);
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}
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if (!optionsArg) {
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// Case: `throw new Error("Some message")` → insert only options
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return appendArguments(
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fixer,
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throwExpression,
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`, { cause: ${caughtError.name} }`,
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);
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}
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return fixExistingOptions(
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optionsArg,
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);
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}
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// Custom error types
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const optionsArg = args[optionsIndex];
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/*
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* Custom error signature is unknown, so skip the suggestion rather
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* than synthesize placeholder values for missing positional args.
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*/
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if (args.length < optionsIndex) {
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return null;
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}
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if (!optionsArg) {
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const lastProvidedArg = args.at(-1);
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if (lastProvidedArg) {
|
|
// Options slot missing, all prior args provided → append options
|
|
return appendArguments(
|
|
fixer,
|
|
throwExpression,
|
|
`, { cause: ${caughtError.name} }`,
|
|
);
|
|
}
|
|
|
|
// argumentPosition: 1 and no args → insert options inside parens
|
|
return addArgumentsToEmptyCall(
|
|
fixer,
|
|
throwExpression,
|
|
`{ cause: ${caughtError.name} }`,
|
|
);
|
|
}
|
|
|
|
return fixExistingOptions(optionsArg);
|
|
},
|
|
},
|
|
],
|
|
});
|
|
|
|
// We don't need to check further
|
|
return;
|
|
}
|
|
|
|
const { value: thrownErrorCause } = errorCauseInfo;
|
|
|
|
// If there is an attached cause, verify that it matches the caught error
|
|
if (!(
|
|
thrownErrorCause.type === "Identifier" &&
|
|
thrownErrorCause.name === caughtError.name
|
|
)) {
|
|
const suggest = errorCauseInfo.multipleDefinitions
|
|
? null // If there are multiple `cause` definitions, a suggestion could be confusing.
|
|
: [
|
|
{
|
|
messageId: "includeCause",
|
|
fix(fixer) {
|
|
/*
|
|
* In case `cause` is attached using object property shorthand or as a method or accessor.
|
|
* e.g. throw Error("fail", { cause });
|
|
* throw Error("fail", { cause() { doSomething(); } });
|
|
* throw Error("fail", { get cause() { return error; } });
|
|
*/
|
|
if (
|
|
thrownErrorCause.parent
|
|
.method ||
|
|
thrownErrorCause.parent
|
|
.shorthand ||
|
|
thrownErrorCause.parent.kind !==
|
|
"init"
|
|
) {
|
|
return fixer.replaceText(
|
|
thrownErrorCause.parent,
|
|
`cause: ${caughtError.name}`,
|
|
);
|
|
}
|
|
|
|
return fixer.replaceText(
|
|
thrownErrorCause,
|
|
caughtError.name,
|
|
);
|
|
},
|
|
},
|
|
];
|
|
context.report({
|
|
messageId: "incorrectCause",
|
|
node: thrownErrorCause,
|
|
suggest,
|
|
});
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* If the attached cause matches the identifier name of the caught error,
|
|
* make sure it is not being shadowed by a closer scoped redeclaration.
|
|
*
|
|
* e.g. try {
|
|
* doSomething();
|
|
* } catch (error) {
|
|
* if (whatever) {
|
|
* const error = anotherError;
|
|
* throw new Error("Something went wrong");
|
|
* }
|
|
* }
|
|
*/
|
|
let scope = sourceCode.getScope(throwStatement);
|
|
do {
|
|
const variable = scope.set.get(caughtError.name);
|
|
if (variable) {
|
|
break;
|
|
}
|
|
scope = scope.upper;
|
|
} while (scope);
|
|
|
|
if (scope?.block !== parentCatch) {
|
|
// Caught error is being shadowed
|
|
context.report({
|
|
messageId: "caughtErrorShadowed",
|
|
node: throwStatement,
|
|
});
|
|
}
|
|
}
|
|
},
|
|
};
|
|
},
|
|
};
|