From 6b543785c89db98e245361876ae62c1d2dda1947 Mon Sep 17 00:00:00 2001
From: Tom Pereira <tom.pereira@johnlewis.co.uk>
Date: Sun, 9 Feb 2025 13:55:22 +0000
Subject: [PATCH] support files ignored by babel

---
 CHANGELOG.md                                  |  3 +++
 package.json                                  |  2 +-
 .../runners/utils/_tests/_transpiler.test.ts  | 25 ++++++++++++++++++-
 source/runner/runners/utils/transpiler.ts     |  4 +--
 4 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 09d844f42..b532635d6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,8 @@
 ## Main
 
 <!-- Your comment below this -->
+Ensure that [babel ignores](https://babeljs.io/docs/options#ignore) do not cause the transpiler to fall over, by supporting the 
+`null` return from `loadOptions` which occurs when a file is ignored.
 <!-- Your comment above this -->
 
 ## 12.3.3
@@ -2118,6 +2120,7 @@ Not usable for others, only stubs of classes etc. - [@orta]
 [@tibdex]: https://github.com/tibdex
 [@tim3trick]: https://github.com/tim3trick
 [@thawankeane]: https://github.com/thawankeane
+[@tomstrepsil: https://github.com/TomStrepsil]
 [@tychota]: https://github.com/tychota
 [@urkle]: https://github.com/urkle
 [@valscion]: https://github.com/valscion
diff --git a/package.json b/package.json
index abf85b9bd..c69258bd3 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "danger",
-  "version": "12.3.3",
+  "version": "12.3.4",
   "description": "Unit tests for Team Culture",
   "main": "distribution/danger.js",
   "typings": "distribution/danger.d.ts",
diff --git a/source/runner/runners/utils/_tests/_transpiler.test.ts b/source/runner/runners/utils/_tests/_transpiler.test.ts
index f50324c52..6aaf45085 100644
--- a/source/runner/runners/utils/_tests/_transpiler.test.ts
+++ b/source/runner/runners/utils/_tests/_transpiler.test.ts
@@ -2,13 +2,15 @@ jest.mock("fs", () => ({
   readFileSync: jest.fn(),
   realpathSync: {},
   existsSync: jest.fn(),
+  statSync: jest.fn(),
+  stat: jest.fn(),
 }))
 jest.mock("path", () => {
   const path = jest.requireActual("path")
   return { ...path, resolve: jest.fn(path.resolve) }
 })
 
-import { typescriptify, lookupTSConfig, dirContains } from "../transpiler"
+import { typescriptify, lookupTSConfig, dirContains, babelify } from "../transpiler"
 import * as fs from "fs"
 import * as path from "path"
 
@@ -87,3 +89,24 @@ describe("dirContains", () => {
     })
   }
 })
+
+describe("babelify", () => {
+  it("does not throw when a filepath is ignored due to babel options, and should return the content unchanged", () => {
+    const dangerfile = "import {a} from 'lodash'; a()"
+
+    const existsSyncMock = fs.existsSync as jest.Mock
+    const actualFs = jest.requireActual("fs") as typeof fs
+    existsSyncMock.mockImplementation((path) => path === "/a/b/babel.config.js" || actualFs.existsSync(path))
+    jest.mock(
+      "/a/b/babel.config.js",
+      () => {
+        return { ignore: ["/a/b"] }
+      },
+      { virtual: true }
+    )
+    const act = () => babelify(dangerfile, "a/b/", [])
+
+    expect(act).not.toThrow()
+    expect(act()).toEqual(dangerfile)
+  })
+})
diff --git a/source/runner/runners/utils/transpiler.ts b/source/runner/runners/utils/transpiler.ts
index 15ca593fd..31e74815a 100644
--- a/source/runner/runners/utils/transpiler.ts
+++ b/source/runner/runners/utils/transpiler.ts
@@ -172,7 +172,7 @@ export const babelify = (content: string, filename: string, extraPlugins: string
     return content
   }
 
-  const options = babel.loadOptions ? babel.loadOptions({ filename }) : { plugins: [] }
+  const options = babel.loadOptions?.({ filename: filename }) ?? { plugins: [] }
 
   const fileOpts = {
     filename,
@@ -186,7 +186,7 @@ export const babelify = (content: string, filename: string, extraPlugins: string
   const result = transformSync(content, fileOpts)
   d("Result from Babel:")
   d(result)
-  return result.code
+  return result?.code ?? content
 }
 
 export default (code: string, filename: string, remoteFile: boolean = false) => {