feat: Add template tests (#9083)

* add template tests

* remove files

* adding validate flow build

* add validate endpoint and flow execution

* Update .github/workflows/template-tests.yml

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* Update src/backend/base/langflow/utils/template_validation.py

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* [autofix.ci] apply automated fixes

* change workflow running

* add ci

* fix test

* fix test

* delete when push

* fix: Exclude template tests from unit test bundle

Template tests are already run separately in CI via the test-templates job.
This change prevents duplicate execution and eliminates timeout failures
in the unit test suite by excluding slow template execution tests.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix: Exclude template tests from unit test bundle

Template tests are already run separately in CI via the test-templates job.
This change prevents duplicate execution and eliminates timeout failures
in the unit test suite by excluding slow template execution tests.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix: Exclude template tests from unit test bundle

Template tests are already run separately in CI via the test-templates job.
This change prevents duplicate execution and eliminates timeout failures
in the unit test suite by excluding slow template execution tests.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix: Remove remaining merge conflict markers

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix: Improve validate.py unit tests to eliminate CI failures

Fixed 4 failing tests in test_validate.py:
- test_code_with_syntax_error: Better error message handling for syntax errors
- test_raises_error_for_missing_function: Handle StopIteration along with ValueError
- test_creates_simple_class: Use optional constructor parameter to avoid TypeError
- test_handles_validation_error: Use proper ValidationError constructor from pydantic_core
- test_creates_context_with_langflow_imports: Remove invalid module patching
- test_creates_mock_classes_on_import_failure: Use proper import mocking

All 50 validate tests now pass consistently, improving CI stability.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* enhance: Add comprehensive edge case tests for template_validation.py

Added 6 additional test cases to improve coverage of template_validation.py:
- test_validate_stream_exception: Tests Graph.validate_stream() exception handling
- test_code_validation_other_exceptions: Tests TypeError/KeyError/AttributeError handling
- test_vertices_sorted_without_end_vertex_events: Tests variable usage tracking
- test_vertex_count_tracking: Tests vertex_count increment paths
- test_empty_lines_in_stream: Tests empty line handling in event streams
- test_event_stream_validation_exception: Tests exception handling in _validate_event_stream

These tests target the remaining 7 uncovered lines to maximize coverage percentage.
Total tests: 40 (all passing)

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>

Makefile

@@ -130,7 +130,9 @@ unit_tests: ## run unit tests
 		EXTRA_ARGS="$$EXTRA_ARGS --ff"; \
 	fi; \
 	uv run pytest src/backend/tests/unit \
-	--ignore=src/backend/tests/integration $$EXTRA_ARGS \
+	--ignore=src/backend/tests/integration \
+	--ignore=src/backend/tests/unit/template \
+	$$EXTRA_ARGS \
 	--instafail -ra -m 'not api_key_required' \
 	--durations-path src/backend/tests/.test_durations \
 	--splitting-algorithm least_duration $(args)
@@ -161,6 +163,14 @@ tests: ## run unit, integration, coverage tests
 	@echo 'Running Coverage Tests...'
 	make coverage
 
+######################
+# TEMPLATE TESTING
+######################
+
+template_tests: ## run all starter project template tests
+	@echo 'Running Starter Project Template Tests...'
+	@uv run pytest src/backend/tests/unit/template/test_starter_projects.py -v
+
 ######################
 # CODE QUALITY
 ######################