feat: fix bug with similar commit hashes.

.github/workflows/test.yml

@@ -8,6 +8,9 @@ on:
   pull_request:
     branches:
       - main
+  pull_request_review:
+    types:
+      - submitted
 
 jobs:
   shellcheck:
@@ -116,6 +119,29 @@ jobs:
         shell:
           bash
 
+  test-similar-base-and-commit-sha:
+    name: Test changed-files similar base and commit sha
+    runs-on: ${{ matrix.platform }}
+    strategy:
+      fail-fast: false
+      max-parallel: 4
+      matrix:
+        platform: [ubuntu-latest, windows-latest, macos-latest, macos-11, ubuntu-18.04, windows-2022]
+
+    steps:
+      - name: Checkout to branch
+        uses: actions/checkout@v3
+
+      - name: Run changed-files with a single commit history
+        id: changed-files
+        uses: ./
+
+      - name: Show output
+        run: |
+          echo '${{ toJSON(steps.changed-files.outputs) }}'
+        shell:
+          bash
+
   test-non-existent-base-sha:
     name: Test changed-files non existent base sha
     runs-on: ${{ matrix.platform }}

diff-sha.sh

@@ -94,6 +94,12 @@ else
   fi
 fi
 
+if [[ -n "$PREVIOUS_SHA" && -n "$CURRENT_SHA" && "$PREVIOUS_SHA" == "$CURRENT_SHA" ]]; then
+  echo "::error::Similar commit hashes detected: previous sha: $PREVIOUS_SHA is equivalent to the current sha: $CURRENT_SHA"
+  echo "::error::You seem to be missing 'fetch-depth: 0' or 'fetch-depth: 2'. See https://github.com/tj-actions/changed-files#usage"
+  exit 1
+fi
+
 echo "::set-output name=target_branch::$TARGET_BRANCH"
 echo "::set-output name=current_branch::$CURRENT_BRANCH"
 echo "::set-output name=previous_sha::$PREVIOUS_SHA"