Fix path handling under windows

Let the unit tests run under macos and windows additionally.

Author: adangel

.github/workflows/test.yml

@@ -12,8 +12,16 @@ on:
 jobs:
   # unit tests
   unit:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ ubuntu-latest, windows-latest, macos-latest ]
+      fail-fast: false
     steps:
     - uses: actions/checkout@v2
+    - name: Set Node.js 12.x
+      uses: actions/[email protected]
+      with:
+        node-version: 12.x
     - run: npm ci
     - run: npm test

dist/index.js

@@ -126,7 +126,7 @@ const determineModifiedFiles = async function(token, sourcePath) {
             }
             const filenames = allFiles.data
                 .filter(f => f.status === 'added' || f.status === 'changed' || f.status === 'modified')
-                .map(f => f.filename)
+                .map(f => path.normalize(f.filename))
                 .filter(f => sourcePath === '.' || f.startsWith(sourcePath));
             if (core.isDebug()) {
                 core.debug(`   after filtering by status and with '${sourcePath}' ${filenames.length} files remain:`);