Change method of obtaining git root (#3214)

CHANGELOG.md

@@ -34,6 +34,7 @@
 - `[jest-circus]`: Throw explicit error when errors happen after test is considered complete ([#8005](https://github.com/facebook/jest/pull/8005))
 - `[expect]` Remove duck typing and obsolete browser support code when comparing DOM nodes and use DOM-Level-3 API instead ([#7995](https://github.com/facebook/jest/pull/7995))
 - `[jest-mock]` Adds a type check to `prototype` to allow mocks of objects with a primitive `prototype` property. ([#8040](https://github.com/facebook/jest/pull/8040))
+- `[jest-changed-files]` Change method of obtaining git root (fixes #3214) ([#8052](https://github.com/facebook/jest/pull/8052))
 
 ### Chore & Maintenance
 

packages/jest-changed-files/src/git.ts

@@ -72,12 +72,12 @@ const adapter: SCMAdapter = {
   },
 
   getRoot: async cwd => {
-    const options = ['rev-parse', '--show-toplevel'];
+    const options = ['rev-parse', '--show-cdup'];
 
     try {
       const result = await execa('git', options, {cwd});
 
-      return result.stdout;
+      return path.join(cwd, result.stdout);
     } catch (e) {
       return null;
     }