Fix: Gracefully handle missing TypeScript dependency

webhintio · Oct 30, 2019 · a55a667 · a55a667
1 parent a4432bf
commit a55a667
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Showing 3 changed files with 38 additions and 15 deletions.
diff --git a/packages/parser-typescript/package.json b/packages/parser-typescript/package.json
@@ -17,6 +17,7 @@
     "@hint/parser-html": "^3.0.11",
     "@hint/parser-jsx": "^1.0.0",
     "@types/node": "^12.7.5",
+    "@types/proxyquire": "^1.3.28",
     "@typescript-eslint/eslint-plugin": "^1.13.0",
     "@typescript-eslint/parser": "^1.12.0",
     "ava": "^2.4.0",
@@ -26,6 +27,7 @@
     "eventemitter2": "^5.0.1",
     "npm-run-all": "^4.1.5",
     "nyc": "^14.1.0",
+    "proxyquire": "^2.1.3",
     "rimraf": "^3.0.0",
     "typescript": "^3.6.4"
   },

diff --git a/packages/parser-typescript/src/parser.ts b/packages/parser-typescript/src/parser.ts
@@ -1,7 +1,6 @@
 /**
  * @fileoverview webhint parser needed to analyze TypeScript files.
  */
-import { parse, AST_NODE_TYPES } from '@typescript-eslint/typescript-estree';
 import { debug as d } from '@hint/utils/dist/src/debug';
 import { Parser } from 'hint/dist/src/lib/types';
 import { Engine } from 'hint/dist/src/lib/engine';
@@ -10,20 +9,30 @@ import { base, combineWalk } from '@hint/parser-javascript/dist/src/walk';
 
 const debug = d(__filename);
 
-// Extend `walk` to skip over most TS-specific nodes.
-for (const type of Object.keys(AST_NODE_TYPES)) {
-    // Ensure `value` of `ClassProperty` instances is walked.
-    if (type === 'ClassProperty') {
-        base[type] = (node: any, st: any, c: any) => {
-            if (node.value) {
-                c(node.value, st);
-            }
-        };
-    }
+let TypeScriptESTree: typeof import('@typescript-eslint/typescript-estree') | null = null;
+
+try {
+    TypeScriptESTree = require('@typescript-eslint/typescript-estree');
+} catch (e) {
+    debug(`Unable to load TypeScript parser: ${e}`);
+}
 
-    // Just ignore anything else
-    if (!base[type]) {
-        base[type] = base.Identifier;
+if (TypeScriptESTree) {
+    // Extend `walk` to skip over most TS-specific nodes.
+    for (const type of Object.keys(TypeScriptESTree.AST_NODE_TYPES)) {
+        // Ensure `value` of `ClassProperty` instances is walked.
+        if (type === 'ClassProperty') {
+            base[type] = (node: any, st: any, c: any) => {
+                if (node.value) {
+                    c(node.value, st);
+                }
+            };
+        }
+
+        // Just ignore anything else
+        if (!base[type]) {
+            base[type] = base.Identifier;
+        }
     }
 }
 
@@ -37,6 +46,10 @@ export default class TypeScriptParser extends Parser<ScriptEvents> {
                 return;
             }
 
+            if (!TypeScriptESTree) {
+                return;
+            }
+
             debug(`Parsing TypeScript file: ${resource}`);
 
             const sourceCode = response.body.content;
@@ -45,7 +58,7 @@ export default class TypeScriptParser extends Parser<ScriptEvents> {
             try {
                 await engine.emitAsync('parse::start::javascript', { resource });
 
-                const result = parse(sourceCode, { jsx, loc: true, useJSXTextNode: jsx });
+                const result = TypeScriptESTree.parse(sourceCode, { jsx, loc: true, useJSXTextNode: jsx });
 
                 await combineWalk(async (walk) => {
                     await engine.emitAsync('parse::end::javascript', {

diff --git a/packages/parser-typescript/tests/tests.ts b/packages/parser-typescript/tests/tests.ts
@@ -7,6 +7,8 @@ import { CallExpression, ScriptEvents } from '@hint/parser-javascript';
 import { base } from '@hint/parser-javascript/dist/src/walk';
 import JSXParser from '@hint/parser-jsx';
 
+import proxyquire = require('proxyquire');
+
 import TypeScriptParser from '../src/parser';
 
 const emitFetchEndTSX = async (engine: Engine<ScriptEvents & HTMLEvents>, content: string) => {
@@ -79,6 +81,12 @@ const walkCallExpressions = async (content: string) => {
     return nodes;
 };
 
+test('It gracefully handles a missing TypeScript dependency', (t) => {
+    t.notThrows(() => {
+        proxyquire('../src/parser', { '@typescript-eslint/typescript-estree': null });
+    });
+});
+
 test('It can parse and skip types to walk ESTree AST nodes', async (t) => {
     const nodes = await walkCallExpressions(`
         type Foo = { bar: string };