fix: get ast-types scope basically working

Author: jedwards1211

src/babel/babelAstTypes.ts

@@ -5,7 +5,6 @@ import * as defaultTypes from '@babel/types'
 import { memoize, omit, mapValues } from 'lodash'
 import fork from 'ast-types/fork'
 import { Fork } from 'ast-types/types'
-import nodePathPlugin from 'ast-types/lib/node-path'
 
 const babelAstTypes: (t?: typeof defaultTypes) => ReturnType<typeof fork> =
   memoize((t: typeof defaultTypes = defaultTypes): ReturnType<typeof fork> => {
@@ -14,8 +13,6 @@ const babelAstTypes: (t?: typeof defaultTypes) => ReturnType<typeof fork> =
       const { builtInTypes, Type } = types
       const { def, or } = Type
 
-      fork.use(nodePathPlugin)
-
       def('Node').field('type', builtInTypes.string)
       def('Comment')
         .field('type', builtInTypes.string)
@@ -118,6 +115,7 @@ const babelAstTypes: (t?: typeof defaultTypes) => ReturnType<typeof fork> =
           )
         }
       }
+      def('Identifier').bases('Pattern')
     }
 
     return fork([babel])

test/astx/bugs_scope.ts

@@ -0,0 +1,17 @@
+import { TransformOptions } from '../../src'
+import { astxTestcase } from '../astxTestcase'
+import { NodePath as AstTypesNodePath } from 'ast-types/lib/node-path'
+import dedent from 'dedent-js'
+
+astxTestcase({
+  file: __filename,
+  input: dedent`
+    const foo = 1;
+  `,
+  parsers: ['babel', 'babel/tsx'],
+  astx: ({ astx, report }: TransformOptions): void => {
+    const path = astx.find`const foo = 1;`.paths[0]
+    report((path as AstTypesNodePath).scope !== null)
+  },
+  expectedReports: [true],
+})

test/astx/scope-testcase.ts

@@ -0,0 +1,51 @@
+import { NodePath as AstTypesNodePath } from 'ast-types/lib/node-path'
+import { Astx } from '../../src'
+import { astxTestcase } from '../astxTestcase'
+import dedent from 'dedent-js'
+
+astxTestcase({
+  file: __filename,
+  input: dedent`
+    const x = 1, y = 2;
+    function foo() {
+      const y = 3;
+      const target = x + y;
+    }
+  `,
+  expected: dedent`
+    const x = 1, y = 2;
+    function foo() {
+      const y = 3;
+      const target = 1 + 3;
+    }
+  `,
+  parsers: ['babel', 'babel/tsx'],
+  astx: ({ astx }) => {
+    for (const { $a, $b } of astx.find`const target = $a + $b`) {
+      inlineNaively($a)
+      inlineNaively($b)
+    }
+  },
+})
+
+/** kludge to gain access to scope */
+type AstxWithScope = Astx & {
+  path: AstTypesNodePath
+}
+
+// inspired by jscodeshift
+function getDeclarator(a: AstxWithScope) {
+  const name = a.path.value.name
+  const bindings = new Astx(
+    a.context,
+    a.path.scope?.lookup(name)?.getBindings()[name]
+  )
+  return bindings
+    .closest((astx) => astx.node.type === 'VariableDeclarator')
+    .at(0)
+}
+
+function inlineNaively(a: Astx) {
+  const val = getDeclarator(a as AstxWithScope).path.get('init').value
+  a.replace(val)
+}