CI: Check py folders for init files

Author: Marenz

.github/workflows/ci-pr.yaml

@@ -11,6 +11,51 @@ env:
   # but sadly `env` can't be used either in `runs-on`.
 
 jobs:
+  validate-structure:
+    name: Validate Python Package Structure
+    runs-on: ubuntu-latest # Using latest as specific version isn't critical here
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Check for __init__.py files
+      run: |
+        echo "Checking if Python package structure mirrors Protobuf structure..."
+        PROTO_BASE="proto/frequenz/api/common"
+        PYTHON_BASE="py/frequenz/api/common"
+        MISSING_INIT=false # Initialize flag
+
+        # Use process substitution to avoid subshell issues with the while loop
+        while IFS= read -r proto_dir; do
+          # Construct the corresponding python path
+          relative_path="${proto_dir#$PROTO_BASE/}"
+          # Handle the base directory case
+          if [ "$proto_dir" == "$PROTO_BASE" ]; then
+             relative_path=""
+          fi
+
+          python_dir="$PYTHON_BASE/$relative_path"
+
+          # Check if the corresponding python directory exists
+          if [ -d "$python_dir" ]; then
+            # Check if __init__.py exists in the python directory
+            if [ ! -f "$python_dir/__init__.py" ]; then
+              echo "Error: Missing __init__.py in $python_dir (corresponding to $proto_dir)"
+              MISSING_INIT=true # Set the flag
+            fi
+          # Optional check for missing python directories
+          # else
+          #   echo "Warning: Python directory $python_dir not found for proto directory $proto_dir"
+          fi
+        done < <(find "$PROTO_BASE" -type d) # Feed find output via process substitution
+
+        # Check the flag after the loop finishes
+        if [ "$MISSING_INIT" = true ]; then
+          echo "Validation failed: Found missing __init__.py files."
+          exit 1
+        else
+          echo "Validation successful: All corresponding Python directories have __init__.py."
+        fi
+
   protolint:
     name: Check proto files with protolint
     runs-on: ubuntu-24.04