Merge pull request #703 from huafu/refac-jest-hoisting

[beta] Use the proper way of mutating a node in a transformer

Author: kulshekhar

src/transformers/README.md

@@ -5,13 +5,9 @@ See https://dev.doctorevidence.com/how-to-write-a-typescript-transform-plugin-fc
 ## Boilerplate
 
 ```ts
-import {
-  TransformationContext,
-  SourceFile,
-  Visitor,
-  Transformer,
-} from 'typescript';
-import { ConfigSet } from '../config-set'
+import { SourceFile, TransformationContext, Transformer, Visitor } from 'typescript'
+
+import { ConfigSet } from '../config/config-set'
 
 // this is a unique identifier for your transformer
 export const name = 'my-transformer'
@@ -26,7 +22,7 @@ export function factory(cs: ConfigSet) {
       // new nodes if we want to leave the node as is, and
       // continue searching through child nodes:
       return ts.visitEachChild(node, visitor, ctx)
-    };
+    }
     return visitor
   }
   // we return the factory expected in CustomTransformers

src/transformers/hoisting.ts src/transformers/hoist-jest.tssrc/transformers/hoisting.ts renamed to src/transformers/hoist-jest.ts

@@ -98,14 +98,17 @@ export function factory(cs: ConfigSet) {
       enter()
 
       // visit each child
-      const resultNode = ts.visitEachChild(node, visitor, ctx)
+      let resultNode = ts.visitEachChild(node, visitor, ctx)
 
       // check if we have something to hoist in this level
       if (hoisted[level] && hoisted[level].length) {
         // re-order children so that hoisted ones appear first
-        // this is actually the main work of this transformer
-        const block = resultNode as Block
-        block.statements = ts.createNodeArray([...hoisted[level], ...block.statements])
+        // this is actually the main job of this transformer
+        const hoistedStmts = hoisted[level]
+        const otherStmts = (resultNode as Block).statements.filter(s => !hoistedStmts.includes(s))
+        const newNode = ts.getMutableClone(resultNode) as Block
+        newNode.statements = ts.createNodeArray([...hoistedStmts, ...otherStmts])
+        resultNode = newNode
       }
 
       // exit the level
@@ -114,7 +117,6 @@ export function factory(cs: ConfigSet) {
       if (shouldHoistNode(resultNode)) {
         // hoist into current level
         hoist(resultNode as Statement)
-        return
       }
 
       // finsally returns the currently visited node

src/transformers/index.ts

@@ -1,5 +1,5 @@
 import { AstTransformerDesc } from '../types'
 
-import * as hoisting from './hoisting'
+import * as hoisting from './hoist-jest'
 
 export const internals: AstTransformerDesc[] = [hoisting]