feat: allow ast transformers to take in addl opts, fix kulshekhar#1942

docs/user/config/astTransformers.md

@@ -7,8 +7,8 @@ TypeScript AST transformers and provide them to `ts-jest` to include into compil
 
 The option is `astTransformers` and it allows ones to specify which 3 types of TypeScript AST transformers to use with `ts-jest`:
 
-- `before` means your transformers get run before TS ones, which means your transformers will get raw TS syntax 
-instead of transpiled syntax (e.g `import` instead of `require` or `define` ).
+- `before` means your transformers get run before TS ones, which means your transformers will get raw TS syntax
+  instead of transpiled syntax (e.g `import` instead of `require` or `define` ).
 - `after` means your transformers get run after TS ones, which gets transpiled syntax.
 - `afterDeclarations` means your transformers get run during `d.ts` generation phase, allowing you to transform output type declarations.
 
@@ -23,11 +23,17 @@ module.exports = {
   globals: {
     'ts-jest': {
       astTransformers: {
-        before: ['my-custom-transformer'],
+        before: [
+          'my-custom-transformer',
+          {
+            path: 'my-custom-transformer-that-needs-extra-opts',
+            options: {},
+          },
+        ],
       },
-    }
-  }
-};
+    },
+  },
+}
 ```
 
 </div><div class="col-md-6" markdown="block">
@@ -40,7 +46,10 @@ module.exports = {
     "globals": {
       "ts-jest": {
         astTransformers: {
-          "before": ["my-custom-transformer"]
+          "before": ["my-custom-transformer", {
+            path: 'my-custom-transformer-that-needs-extra-opts',
+            options: {}
+          }]
         }
       }
     }
@@ -55,9 +64,9 @@ module.exports = {
 `ts-jest` is able to expose transformers for public usage to provide the possibility to opt-in/out for users. Currently
 the exposed transformers are:
 
-- `path-mapping` convert alias import/export to relative import/export path base on `paths` in `tsconfig`. 
-This transformer works similar to `moduleNameMapper` in `jest.config.js`. When using this transformer, one might not need
-`moduleNameMapper` anymore.
+- `path-mapping` convert alias import/export to relative import/export path base on `paths` in `tsconfig`.
+  This transformer works similar to `moduleNameMapper` in `jest.config.js`. When using this transformer, one might not need
+  `moduleNameMapper` anymore.
 
 #### Example of opt-in transformers
 
@@ -72,9 +81,9 @@ module.exports = {
       astTransformers: {
         before: ['ts-jest/dist/transformers/path-mapping'],
       },
-    }
-  }
-};
+    },
+  },
+}
 ```
 
 </div><div class="col-md-6" markdown="block">
@@ -97,7 +106,6 @@ module.exports = {
 
 </div></div>
 
-
 ### Writing custom TypeScript AST transformers
 
 To write a custom TypeScript AST transformers, one can take a look at [the one](https://github.com/kulshekhar/ts-jest/tree/master/src/transformers) that `ts-jest` is using.

e2e/__tests__/path-mapping.test.ts

@@ -13,7 +13,7 @@ function executeTest(rootDirs?: string[]) {
       },
       astTransformers: {
         before: [
-          'ts-jest/dist/transformers/path-mapping'
+          {path: 'ts-jest/dist/transformers/path-mapping'}
         ],
       },
     },