Support for relative imports to reuse step impls

Signed-off-by: Kunal Vishwasrao <kunal.vishwasrao@gmail.com>

getgauge/impl_loader.py

@@ -6,6 +6,7 @@
 import sys
 import traceback
 from os import path
+from contextlib import contextmanager
 
 from getgauge import logger
 from getgauge.registry import registry
@@ -16,6 +17,7 @@
 env_dir = os.path.join(project_root, 'env', 'default')
 requirements_file = os.path.join(project_root, 'requirements.txt')
 sys.path.append(project_root)
+temporary_sys_path = []
 PLUGIN_JSON = 'python.json'
 VERSION = 'version'
 PYTHON_PROPERTIES = 'python.properties'
@@ -30,6 +32,12 @@ def load_impls(step_impl_dirs=impl_dirs):
             logger.error('Make sure `STEP_IMPL_DIR` env var is set to a valid directory path.')
             return
         base_dir = project_root if impl_dir.startswith(project_root) else os.path.dirname(impl_dir)
+        # Handle multi-level relative imports
+        for _ in range(impl_dir.count('..')):
+            base_dir = os.path.dirname(base_dir).replace("/", os.path.sep).replace("\\", os.path.sep)
+        # Add temporary sys path for relative imports that is not already added
+        if '..' in impl_dir and base_dir not in temporary_sys_path:
+            temporary_sys_path.append(base_dir)
         _import_impl(base_dir, impl_dir)
 
 
@@ -57,12 +65,25 @@ def _import_impl(base_dir, step_impl_dir):
         elif path.isdir(file_path):
             _import_impl(base_dir, file_path)
 
+@contextmanager
+def use_temporary_sys_path():
+    original_sys_path = sys.path[:]
+    sys.path.extend(temporary_sys_path)
+    try:
+        yield
+    finally:
+        sys.path = original_sys_path
 
 def _import_file(base_dir, file_path):
     rel_path = os.path.normpath(file_path.replace(base_dir + os.path.sep, ''))
     try:
         module_name = os.path.splitext(rel_path.replace(os.path.sep, '.'))[0]
-        m = importlib.import_module(module_name)
+        # Use temporary sys path for relative imports
+        if '..' in file_path:
+            with use_temporary_sys_path():
+                m = importlib.import_module(module_name)
+        else:
+            m = importlib.import_module(module_name)
         # Get all classes in the imported module
         classes = inspect.getmembers(m, lambda member: inspect.isclass(member) and member.__module__ == module_name)
         if len(classes) > 0:

python.json

@@ -1,6 +1,6 @@
 {
   "id": "python",
-  "version": "0.4.3",
+  "version": "0.4.4",
   "description": "Python support for gauge",
   "run": {
     "windows": [