ci: make bazel test incremental

.github/workflows/bazel_test.yml

@@ -1,3 +1,4 @@
+# yamllint disable rule:line-length
 ---
 name: Bazel Test
 on:  # yamllint disable-line rule:truthy
@@ -7,8 +8,41 @@ jobs:
   bazel_test:
     runs-on: ubuntu-latest
     steps:
-      - name: Cache bazel
-        uses: actions/cache@v2
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Find affected files
+        id: affected_files
+        run: |
+          git fetch origin ${{ github.base_ref }} --depth=1
+          git diff --name-only origin/${{ github.base_ref }} > affected_files.txt
+          echo "Affected files:"
+          cat affected_files.txt
+
+      - name: Find affected Bazel targets
+        id: bazel_targets
+        run: |
+          > affected_targets.txt
+
+          while read file; do
+            if [[ -f $file ]]; then
+              if [[ "$file" == *.cpp || "$file" == *.h || "$file" == *.hpp || "$file" == *.cc || "$file" == *.cxx || "$file" == *.hxx ]]; then
+                echo "Finding targets for: $file"
+                targets=$(bazel query --output=package "$file" || true)/...
+                echo "$targets" >> affected_targets.txt
+              fi
+            fi
+          done < affected_files.txt
+
+          sort -u affected_targets.txt -o affected_targets.txt
+          echo "Affected targets:"
+          cat affected_targets.txt
+
+          echo "targets=$(cat affected_targets.txt | tr '\n' ' ')" >> $GITHUB_ENV
+
+      - name: Setup bazel cache
+        if: env.targets != ''
+        uses: actions/cache@v3
         env:
           cache-name: bazel-cache
         with:
@@ -18,8 +52,13 @@ jobs:
           key: ${{ runner.os }}-${{ env.cache-name }}-${{ github.ref }}
           restore-keys: |
             ${{ runner.os }}-${{ env.cache-name }}-development
-      - name: Checkout code
-        uses: actions/checkout@v3
-      - name: Run Bazel test
-        run: |-
-          bazel test //...
+
+      - name: Test affected targets
+        if: env.targets != ''
+        run: |
+          echo "Building targets: $targets"
+          bazel test ${targets}
+
+      - name: No targets to test
+        if: env.targets == ''
+        run: echo "No affected Bazel targets found. Skipping test."