Breaking: align babel-eslint-parser & espree (#11137)

* Chore: align babel-eslint-parser & espree

* Start program at beginning of comment when no tokens exist

* Import correct version of Espree for tests

* Remove hasOwnProperty guard

eslint/babel-eslint-parser/package.json

@@ -31,7 +31,6 @@
     "@babel/core": "^7.2.0",
     "@babel/eslint-shared-fixtures": "*",
     "eslint": "^6.0.1",
-    "espree": "^6.0.0",
     "lodash.clonedeep": "^4.5.0"
   }
 }

eslint/babel-eslint-parser/src/convert/convertAST.js

@@ -1,14 +1,10 @@
 import { types as t, traverse } from "@babel/core";
 
 function convertNodes(ast, code) {
-  const state = { source: code };
   const astTransformVisitor = {
     noScope: true,
     enter(path) {
-      const node = path.node;
-
-      // private var to track original node type
-      node._babelType = node.type;
+      const { node } = path;
 
       if (node.innerComments) {
         delete node.innerComments;
@@ -23,7 +19,16 @@ function convertNodes(ast, code) {
       }
     },
     exit(path) {
-      const node = path.node;
+      const { node } = path;
+
+      // Used internally by @babel/parser.
+      if (node.extra) {
+        delete node.extra;
+      }
+
+      if (node?.loc.identifierName) {
+        delete node.loc.identifierName;
+      }
 
       if (path.isTypeParameter()) {
         node.type = "Identifier";
@@ -74,6 +79,7 @@ function convertNodes(ast, code) {
       }
     },
   };
+  const state = { source: code };
 
   // Monkey patch visitor keys in order to be able to traverse the estree nodes
   t.VISITOR_KEYS.Property = t.VISITOR_KEYS.ObjectProperty;
@@ -95,19 +101,14 @@ function convertNodes(ast, code) {
 function convertProgramNode(ast) {
   ast.type = "Program";
   ast.sourceType = ast.program.sourceType;
-  ast.directives = ast.program.directives;
   ast.body = ast.program.body;
   delete ast.program;
+  delete ast.errors;
 
   if (ast.comments.length) {
     const lastComment = ast.comments[ast.comments.length - 1];
 
-    if (!ast.tokens.length) {
-      // if no tokens, the program starts at the end of the last comment
-      ast.start = lastComment.end;
-      ast.loc.start.line = lastComment.loc.end.line;
-      ast.loc.start.column = lastComment.loc.end.column;
-    } else {
+    if (ast.tokens.length) {
       const lastToken = ast.tokens[ast.tokens.length - 1];
 
       if (lastComment.end > lastToken.end) {

eslint/babel-eslint-parser/src/convert/convertComments.js

@@ -1,6 +1,5 @@
 export default function convertComments(comments) {
-  for (let i = 0; i < comments.length; i++) {
-    const comment = comments[i];
+  for (const comment of comments) {
     if (comment.type === "CommentBlock") {
       comment.type = "Block";
     } else if (comment.type === "CommentLine") {

eslint/babel-eslint-parser/test/helpers/assert-implements-ast.js

@@ -1,40 +0,0 @@
-// Checks if the source ast implements the target ast. Ignores extra keys on source ast
-export default function assertImplementsAST(target, source, path) {
-  if (!path) {
-    path = [];
-  }
-
-  function error(text) {
-    const err = new Error(`At ${path.join(".")}: ${text}:`);
-    err.depth = path.length + 1;
-    throw err;
-  }
-
-  const typeA = target === null ? "null" : typeof target;
-  const typeB = source === null ? "null" : typeof source;
-  if (typeA !== typeB) {
-    error(
-      `have different types (${typeA} !== ${typeB}) (${target} !== ${source})`,
-    );
-  } else if (
-    typeA === "object" &&
-    ["RegExp"].indexOf(target.constructor.name) !== -1 &&
-    target.constructor.name !== source.constructor.name
-  ) {
-    error(
-      `object have different constructors (${target.constructor.name} !== ${source.constructor.name}`,
-    );
-  } else if (typeA === "object") {
-    const keysTarget = Object.keys(target);
-    for (const i in keysTarget) {
-      const key = keysTarget[i];
-      path.push(key);
-      assertImplementsAST(target[key], source[key], path);
-      path.pop();
-    }
-  } else if (target !== source) {
-    error(
-      `are different (${JSON.stringify(target)} !== ${JSON.stringify(source)})`,
-    );
-  }
-}

eslint/babel-eslint-parser/test/index.js

@@ -1,54 +1,88 @@
-import assert from "assert";
-import espree from "espree";
+import path from "path";
 import escope from "eslint-scope";
 import unpad from "dedent";
 import { parseForESLint } from "../src";
-import assertImplementsAST from "./helpers/assert-implements-ast";
 
-const babelOptions = {
+const BABEL_OPTIONS = {
   configFile: require.resolve(
     "@babel/eslint-shared-fixtures/config/babel.config.js",
   ),
 };
+const ALLOWED_PROPERTIES = [
+  "importKind",
+  "exportKind",
+  "variance",
+  "typeArguments",
+];
 
-function parseAndAssertSame(code) {
-  code = unpad(code);
-  const esAST = espree.parse(code, {
-    ecmaFeatures: {
-      // enable JSX parsing
-      jsx: true,
-      // enable return in global scope
-      globalReturn: true,
-      // enable implied strict mode (if ecmaVersion >= 5)
-      impliedStrict: true,
-      // allow experimental object rest/spread
-      experimentalObjectRestSpread: true,
-    },
-    tokens: true,
-    loc: true,
-    range: true,
-    comment: true,
-    ecmaVersion: 2020,
-    sourceType: "module",
-  });
-  const babylonAST = parseForESLint(code, {
-    eslintVisitorKeys: true,
-    eslintScopeManager: true,
-    babelOptions,
-  }).ast;
-  assertImplementsAST(esAST, babylonAST);
+function deeplyRemoveProperties(obj, props) {
+  for (const [k, v] of Object.entries(obj)) {
+    if (typeof v === "object") {
+      if (Array.isArray(v)) {
+        for (const el of v) {
+          if (el != null) deeplyRemoveProperties(el, props);
+        }
+      }
+
+      if (props.includes(k)) delete obj[k];
+      else if (v != null) deeplyRemoveProperties(v, props);
+      continue;
+    }
+
+    if (props.includes(k)) delete obj[k];
+  }
 }
 
-describe("babylon-to-espree", () => {
+describe("Babel and Espree", () => {
+  let espree;
+
+  function parseAndAssertSame(code) {
+    code = unpad(code);
+    const espreeAST = espree.parse(code, {
+      ecmaFeatures: {
+        // enable JSX parsing
+        jsx: true,
+        // enable return in global scope
+        globalReturn: true,
+        // enable implied strict mode (if ecmaVersion >= 5)
+        impliedStrict: true,
+        // allow experimental object rest/spread
+        experimentalObjectRestSpread: true,
+      },
+      tokens: true,
+      loc: true,
+      range: true,
+      comment: true,
+      ecmaVersion: 2020,
+      sourceType: "module",
+    });
+    const babelAST = parseForESLint(code, {
+      eslintVisitorKeys: true,
+      eslintScopeManager: true,
+      babelOptions: BABEL_OPTIONS,
+    }).ast;
+    deeplyRemoveProperties(babelAST, ALLOWED_PROPERTIES);
+    expect(babelAST).toEqual(espreeAST);
+  }
+
+  beforeAll(async () => {
+    // Use the version of Espree that is a dependency of
+    // the version of ESLint we are testing against.
+    const espreePath = require.resolve("espree", {
+      paths: [path.dirname(require.resolve("eslint"))],
+    });
+    espree = await import(espreePath);
+  });
+
   describe("compatibility", () => {
     it("should allow ast.analyze to be called without options", function() {
-      const esAST = parseForESLint("`test`", {
+      const ast = parseForESLint("`test`", {
         eslintScopeManager: true,
         eslintVisitorKeys: true,
-        babelOptions,
+        babelOptions: BABEL_OPTIONS,
       }).ast;
       expect(() => {
-        escope.analyze(esAST);
+        escope.analyze(ast);
       }).not.toThrow(new TypeError("Should allow no options argument."));
     });
   });
@@ -244,9 +278,9 @@ describe("babylon-to-espree", () => {
     const babylonAST = parseForESLint(code, {
       eslintVisitorKeys: true,
       eslintScopeManager: true,
-      babelOptions,
+      babelOptions: BABEL_OPTIONS,
     }).ast;
-    assert.strictEqual(babylonAST.tokens[1].type, "Punctuator");
+    expect(babylonAST.tokens[1].type).toEqual("Punctuator");
   });
 
   // Espree doesn't support the nullish coalescing operator yet
@@ -255,9 +289,9 @@ describe("babylon-to-espree", () => {
     const babylonAST = parseForESLint(code, {
       eslintVisitorKeys: true,
       eslintScopeManager: true,
-      babelOptions,
+      babelOptions: BABEL_OPTIONS,
     }).ast;
-    assert.strictEqual(babylonAST.tokens[1].type, "Punctuator");
+    expect(babylonAST.tokens[1].type).toEqual("Punctuator");
   });
 
   // Espree doesn't support the pipeline operator yet
@@ -266,9 +300,9 @@ describe("babylon-to-espree", () => {
     const babylonAST = parseForESLint(code, {
       eslintVisitorKeys: true,
       eslintScopeManager: true,
-      babelOptions,
+      babelOptions: BABEL_OPTIONS,
     }).ast;
-    assert.strictEqual(babylonAST.tokens[1].type, "Punctuator");
+    expect(babylonAST.tokens[1].type).toEqual("Punctuator");
   });
 
   // Espree doesn't support private fields yet
@@ -277,19 +311,17 @@ describe("babylon-to-espree", () => {
     const babylonAST = parseForESLint(code, {
       eslintVisitorKeys: true,
       eslintScopeManager: true,
-      babelOptions,
+      babelOptions: BABEL_OPTIONS,
     }).ast;
-    assert.strictEqual(babylonAST.tokens[3].type, "Punctuator");
-    assert.strictEqual(babylonAST.tokens[3].value, "#");
+    expect(babylonAST.tokens[3].type).toEqual("Punctuator");
+    expect(babylonAST.tokens[3].value).toEqual("#");
   });
 
-  // eslint-disable-next-line jest/no-disabled-tests
-  it.skip("empty program with line comment", () => {
+  it("empty program with line comment", () => {
     parseAndAssertSame("// single comment");
   });
 
-  // eslint-disable-next-line jest/no-disabled-tests
-  it.skip("empty program with block comment", () => {
+  it("empty program with block comment", () => {
     parseAndAssertSame("  /* multiline\n * comment\n*/");
   });
 
@@ -448,9 +480,13 @@ describe("babylon-to-espree", () => {
     });
 
     it("do not allow import export everywhere", () => {
-      assert.throws(() => {
+      expect(() => {
         parseAndAssertSame('function F() { import a from "a"; }');
-      }, /SyntaxError: 'import' and 'export' may only appear at the top level/);
+      }).toThrow(
+        new SyntaxError(
+          "'import' and 'export' may only appear at the top level",
+        ),
+      );
     });
 
     it("return outside function", () => {
@@ -458,9 +494,9 @@ describe("babylon-to-espree", () => {
     });
 
     it("super outside method", () => {
-      assert.throws(() => {
+      expect(() => {
         parseAndAssertSame("function F() { super(); }");
-      }, /SyntaxError: 'super' keyword outside a method/);
+      }).toThrow(new SyntaxError("'super' keyword outside a method"));
     });
 
     it("StringLiteral", () => {