Use runtime constraints

examples/async_step/features/async_dispatch.feature

@@ -1,6 +1,8 @@
 @use.with_python.version=3.4
 @use.with_python.version=3.5
 @use.with_python.version=3.6
+@use.with_python.version=3.7
+@use.with_python.version=3.8
 Feature:
   Scenario:
     Given I dispatch an async-call with param "Alice"

examples/async_step/features/async_run.feature

@@ -1,6 +1,8 @@
 @use.with_python.version=3.4
 @use.with_python.version=3.5
 @use.with_python.version=3.6
+@use.with_python.version=3.7
+@use.with_python.version=3.8
 Feature:
   Scenario:
     Given an async-step waits 0.3 seconds

examples/async_step/features/environment.py

@@ -1,8 +1,18 @@
 # -*- coding: UTF-8 -*-
 
 from behave.tag_matcher import ActiveTagMatcher, setup_active_tag_values
+from behave.api.runtime_constraint import require_min_python_version
 import sys
 
+# -----------------------------------------------------------------------------
+# REQUIRE: python >= 3.4
+# -----------------------------------------------------------------------------
+require_min_python_version("3.4")
+
+
+# -----------------------------------------------------------------------------
+# SUPPORT: Active-tags
+# -----------------------------------------------------------------------------
 # -- MATCHES ANY TAGS: @use.with_{category}={value}
 # NOTE: active_tag_value_provider provides category values for active tags.
 python_version = "%s.%s" % sys.version_info[:2]
@@ -11,17 +21,20 @@
 }
 active_tag_matcher = ActiveTagMatcher(active_tag_value_provider)
 
+
 # -----------------------------------------------------------------------------
 # HOOKS:
 # -----------------------------------------------------------------------------
 def before_all(context):
     # -- SETUP ACTIVE-TAG MATCHER (with userdata):
     setup_active_tag_values(active_tag_value_provider, context.config.userdata)
 
+
 def before_feature(context, feature):
     if active_tag_matcher.should_exclude_with(feature.tags):
         feature.skip(reason=active_tag_matcher.exclude_reason)
 
+
 def before_scenario(context, scenario):
     if active_tag_matcher.should_exclude_with(scenario.effective_tags):
         scenario.skip(reason=active_tag_matcher.exclude_reason)

examples/async_step/features/steps/async_steps34.py → examples/async_step/features/steps/_async_steps34.py

@@ -1,8 +1,12 @@
-# -- REQUIRES: Python >= 3.4
+# -- REQUIRES: Python >= 3.4 and Python < 3.8
+# HINT: Decorator @asyncio.coroutine is prohibited in python 3.8
+# USE:  Async generator/coroutine instead.
+
 from behave import step
 from behave.api.async_step import async_run_until_complete
 import asyncio
 
+# -- USABLE FOR: "3.4" <= python_version < "3.8"
 @step('an async-step waits {duration:f} seconds')
 @async_run_until_complete
 @asyncio.coroutine

examples/async_step/features/steps/async_steps35.py → examples/async_step/features/steps/_async_steps35.py

@@ -1,10 +1,11 @@
 # -- REQUIRES: Python >= 3.5
+
 from behave import step
 from behave.api.async_step import async_run_until_complete
 import asyncio
 
 @step('an async-step waits {duration:f} seconds')
 @async_run_until_complete
 async def step_async_step_waits_seconds_py35(context, duration):
-    """Simple example of a coroutine as async-step (in Python 3.5)"""
+    """Simple example of a coroutine as async-step (in Python 3.5 or newer)"""
     await asyncio.sleep(duration)

examples/async_step/features/steps/async_dispatch_steps.py

@@ -1,21 +1,38 @@
 # -*- coding: UTF-8 -*-
-# REQUIRES: Python >= 3.5
+# REQUIRES: Python >= 3.4/3.5
+import sys
 from behave import given, then, step
-from behave.api.async_step import use_or_create_async_context, AsyncContext
+from behave.api.async_step import use_or_create_async_context
 from hamcrest import assert_that, equal_to, empty
 import asyncio
 
-@asyncio.coroutine
-def async_func(param):
-    yield from asyncio.sleep(0.2)
-    return str(param).upper()
 
+# ---------------------------------------------------------------------------
+# ASYNC EXAMPLE FUNCTION:
+# ---------------------------------------------------------------------------
+python_version = "%s.%s" % sys.version_info[:2]
+if python_version >= "3.5":
+    async def async_func(param):
+        await asyncio.sleep(0.2)
+        return str(param).upper()
+else:
+    # -- HINT: Decorator @asyncio.coroutine is prohibited in python 3.8
+    @asyncio.coroutine
+    def async_func(param):
+        yield from asyncio.sleep(0.2)
+        return str(param).upper()
+
+
+# ---------------------------------------------------------------------------
+# STEPS:
+# ---------------------------------------------------------------------------
 @given('I dispatch an async-call with param "{param}"')
 def step_dispatch_async_call(context, param):
     async_context = use_or_create_async_context(context, "async_context1")
     task = async_context.loop.create_task(async_func(param))
     async_context.tasks.append(task)
 
+
 @then('the collected result of the async-calls is "{expected}"')
 def step_collected_async_call_result_is(context, expected):
     async_context = context.async_context1

examples/async_step/features/steps/async_steps.py

@@ -0,0 +1,12 @@
+# -*- coding: UTF-8 -*-
+# REQUIRES: Python >= 3.4/3.5
+"""Python import-barrier for python2 or python < 3.4."""
+
+from __future__ import absolute_import
+import sys
+
+python_version = "%s.%s" % sys.version_info[:2]
+if python_version >= "3.5":
+    import _async_steps35
+elif python_version == "3.4":
+    import _async_steps34