ci: add smart change detection to CircleCI nodes to skip unnecessary tests

Add should_run_tests() helper function that checks if relevant files changed
since origin/master before running each node's integration tests.

Decision logic (in order):
1. If origin/master unavailable (fresh CI env) → run tests (safe default)
2. If git diff fails → run tests (safe default)
3. If generator/config changed (modules/, bin/configs/, pom.xml, .mvn/) → run tests
4. If node's sample directories changed → run tests
5. Otherwise → skip tests

Logs the decision-making process clearly for each node so users can
understand why tests ran or were skipped.

Prevents wasted CI resources on pure .github/ changes or unrelated sample
changes (e.g., don't run perl tests if only ruby sample changed).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Picazsoo

CI/circle_parallel.sh

@@ -9,36 +9,107 @@ set -e
 
 export NODE_ENV=test
 
+# Helper function to check if tests should run for this node based on changed files
+should_run_tests() {
+  local node_index=$1
+  local sample_patterns=$2  # space-separated glob patterns for samples this node tests
+
+  echo ""
+  echo "════════════════════════════════════════════════════════════════"
+  echo "Node $node_index: Determining if tests should run"
+  echo "════════════════════════════════════════════════════════════════"
+
+  # Always run tests if origin/master doesn't exist (e.g., fresh CI environment)
+  if ! git rev-parse origin/master >/dev/null 2>&1; then
+    echo "ℹ️  origin/master not available locally (fresh checkout or CI environment)"
+    echo "✓ DECISION: Running tests (cannot determine changes safely)"
+    return 0
+  fi
+
+  # Try to get list of changed files since origin/master
+  local changed
+  changed=$(git diff --name-only origin/master HEAD 2>/dev/null) || {
+    echo "⚠️  git diff origin/master HEAD failed"
+    echo "✓ DECISION: Running tests (cannot determine changes safely)"
+    return 0
+  }
+
+  if [ -z "$changed" ]; then
+    echo "ℹ️  No files changed since origin/master"
+    echo "✗ DECISION: Skipping tests (nothing to test)"
+    return 1
+  fi
+
+  echo "Changed files:"
+  echo "$changed" | sed 's/^/  /'
+
+  # Check if generator source or config changed (affects all samples)
+  echo ""
+  echo "Checking for generator/config changes (affects all samples)..."
+  if echo "$changed" | grep -qE '^(modules/|bin/configs/|pom\.xml|\.mvn/)'; then
+    echo "✓ Found: generator or config files changed"
+    echo "✓ DECISION: Running tests (generator/config affects all samples)"
+    return 0
+  fi
+
+  # Check if this node's sample directories changed
+  echo ""
+  echo "Checking for sample changes relevant to this node..."
+  for pattern in $sample_patterns; do
+    if echo "$changed" | grep -q "^$pattern"; then
+      echo "✓ Found: $pattern"
+      echo "✓ DECISION: Running tests (relevant sample changed)"
+      return 0
+    fi
+  done
+
+  echo "✗ No relevant sample changes found for node $node_index"
+  echo "✗ DECISION: Skipping tests (no relevant changes)"
+  return 1
+}
+
 if [ "$NODE_INDEX" = "1" ]; then
   echo "Running node $NODE_INDEX ..."
 
-  sudo apt-get -y install cpanminus
+  if should_run_tests "$NODE_INDEX" "samples/client/petstore/perl/"; then
+    sudo apt-get -y install cpanminus
 
-  echo "Testing perl"
-  (cd samples/client/petstore/perl && /bin/bash ./test.bash)
+    echo "Testing perl"
+    (cd samples/client/petstore/perl && /bin/bash ./test.bash)
+  else
+    echo "Skipping perl tests — no relevant changes"
+  fi
 
 
 elif [ "$NODE_INDEX" = "2" ]; then
   echo "Running node $NODE_INDEX to test cpp-restsdk"
 
-  # install cpprestsdk
-  sudo apt-get install libcpprest-dev
-  wget "https://github.com/aminya/setup-cpp/releases/download/v0.37.0/setup-cpp-x64-linux"
-  chmod +x ./setup-cpp-x64-linux
-  sudo ./setup-cpp-x64-linux --compiler llvm --cmake true --ninja true
-  source ~/.cpprc # activate cpp environment variables
+  if should_run_tests "$NODE_INDEX" "samples/client/petstore/cpp-restsdk/"; then
+    # install cpprestsdk
+    sudo apt-get install libcpprest-dev
+    wget "https://github.com/aminya/setup-cpp/releases/download/v0.37.0/setup-cpp-x64-linux"
+    chmod +x ./setup-cpp-x64-linux
+    sudo ./setup-cpp-x64-linux --compiler llvm --cmake true --ninja true
+    source ~/.cpprc # activate cpp environment variables
 
-  (cd samples/client/petstore/cpp-restsdk/client && mvn integration-test)
+    (cd samples/client/petstore/cpp-restsdk/client && mvn integration-test)
+  else
+    echo "Skipping cpp-restsdk tests — no relevant changes"
+  fi
 
 elif [ "$NODE_INDEX" = "3" ]; then
 
   echo "Running node $NODE_INDEX ... "
 
-  echo "Testing ruby"
-  (cd samples/client/petstore/ruby && mvn integration-test)
-  (cd samples/client/petstore/ruby-faraday && mvn integration-test)
-  (cd samples/client/petstore/ruby-httpx && mvn integration-test)
-  (cd samples/client/petstore/ruby-autoload && mvn integration-test)
+  if should_run_tests "$NODE_INDEX" "samples/client/petstore/ruby"; then
+    echo "Testing ruby"
+    (cd samples/client/petstore/ruby && mvn integration-test)
+    (cd samples/client/petstore/ruby-faraday && mvn integration-test)
+    (cd samples/client/petstore/ruby-httpx && mvn integration-test)
+    (cd samples/client/petstore/ruby-autoload && mvn integration-test)
+  else
+    echo "Skipping ruby tests — no relevant changes"
+  fi
 
 else
   echo "Running node $NODE_INDEX ..."