From 57c7af0bd6e12cb683894c39303affa2111f8ea0 Mon Sep 17 00:00:00 2001
From: Ahn <anhpnnd@gmail.com>
Date: Mon, 30 Mar 2020 19:30:15 +0200
Subject: [PATCH] fix(config): set default outDir for enabled allowJs without
 outDir (#1472)

---
 src/config/config-set.spec.ts | 4 ++++
 src/config/config-set.ts      | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/src/config/config-set.spec.ts b/src/config/config-set.spec.ts
index fa7593768a..bee8825f0c 100644
--- a/src/config/config-set.spec.ts
+++ b/src/config/config-set.spec.ts
@@ -495,6 +495,10 @@ describe('typescript', () => {
     })
   })
 
+  it('should include default outDir $$ts-jest$$ when allowJs is enabled and no outDir from config', () => {
+    expect(get(void 0, { tsConfig: { allowJs: true } }).options.outDir).toBe('$$ts-jest$$')
+  })
+
   it('should be able to read extends', () => {
     const cs = createConfigSet({
       tsJestConfig: { tsConfig: 'tsconfig.build.json' },
diff --git a/src/config/config-set.ts b/src/config/config-set.ts
index 47214ab300..c75f7fbaa8 100644
--- a/src/config/config-set.ts
+++ b/src/config/config-set.ts
@@ -714,6 +714,10 @@ export class ConfigSet {
         finalOptions.allowSyntheticDefaultImports = true
       }
     }
+    // Make sure when allowJs is enabled, outDir is set otherwise we run into error: Cannot write file ... because it would overwrite input
+    if (finalOptions.allowJs && !finalOptions.outDir) {
+      finalOptions.outDir = '$$ts-jest$$'
+    }
 
     // ensure undefined are removed and other values are overridden
     for (const key of Object.keys(forcedOptions)) {