Add test to make sure that converter for parser for empty strings in example tables works as expected

Resolves #551

Author: jsa34

tests/feature/test_outline_empty_values.py

@@ -4,28 +4,6 @@
 
 from pytest_bdd.utils import collect_dumped_objects
 
-STEPS = """\
-from pytest_bdd import given, when, then, parsers
-from pytest_bdd.utils import dump_obj
-
-# Using `parsers.re` so that we can match empty values
-
-@given(parsers.re("there are (?P<start>.*?) cucumbers"))
-def _(start):
-    dump_obj(start)
-
-
-@when(parsers.re("I eat (?P<eat>.*?) cucumbers"))
-def _(eat):
-    dump_obj(eat)
-
-
-@then(parsers.re("I should have (?P<left>.*?) cucumbers"))
-def _(left):
-    dump_obj(left)
-
-"""
-
 
 def test_scenario_with_empty_example_values(pytester):
     pytester.makefile(
@@ -44,14 +22,36 @@ def test_scenario_with_empty_example_values(pytester):
             """
         ),
     )
-    pytester.makeconftest(textwrap.dedent(STEPS))
+    pytester.makeconftest(
+        textwrap.dedent(
+            """\
+            from pytest_bdd import given, when, then, parsers
+            from pytest_bdd.utils import dump_obj
+
+            # Using `parsers.re` so that we can match empty values
+
+            @given(parsers.re("there are (?P<start>.*?) cucumbers"))
+            def _(start):
+                dump_obj(start)
+
+
+            @when(parsers.re("I eat (?P<eat>.*?) cucumbers"))
+            def _(eat):
+                dump_obj(eat)
+
+
+            @then(parsers.re("I should have (?P<left>.*?) cucumbers"))
+            def _(left):
+                dump_obj(left)
+
+            """
+        )
+    )
 
     pytester.makepyfile(
         textwrap.dedent(
             """\
-        from pytest_bdd.utils import dump_obj
         from pytest_bdd import scenario
-        import json
 
         @scenario("outline.feature", "Outlined with empty example values")
         def test_outline():
@@ -62,3 +62,65 @@ def test_outline():
     result = pytester.runpytest("-s")
     result.assert_outcomes(passed=1)
     assert collect_dumped_objects(result) == ["#", "", ""]
+
+
+def test_scenario_with_empty_example_values_none_transformer(pytester):
+    pytester.makefile(
+        ".feature",
+        outline=textwrap.dedent(
+            """\
+            Feature: Outline
+                Scenario Outline: Outlined with empty example values and transformer
+                    Given there are <start> cucumbers
+                    When I eat <eat> cucumbers
+                    Then I should have <left> cucumbers
+
+                    Examples:
+                    | start | eat | left |
+                    | #     |     |      |
+            """
+        ),
+    )
+    pytester.makeconftest(
+        textwrap.dedent(
+            """\
+            from pytest_bdd import given, when, then, parsers
+            from pytest_bdd.utils import dump_obj
+
+
+            def empty_to_none(value):
+                return None if value.strip() == "" else value
+
+
+            @given(parsers.re("there are (?P<start>.*?) cucumbers"), converters={"start": empty_to_none})
+            def _(start):
+                dump_obj(start)
+
+
+            @when(parsers.re("I eat (?P<eat>.*?) cucumbers"), converters={"eat": empty_to_none})
+            def _(eat):
+                dump_obj(eat)
+
+
+            @then(parsers.re("I should have (?P<left>.*?) cucumbers"), converters={"left": empty_to_none})
+            def _(left):
+                dump_obj(left)
+
+            """
+        )
+    )
+
+    pytester.makepyfile(
+        textwrap.dedent(
+            """\
+            from pytest_bdd import scenario
+
+            @scenario("outline.feature", "Outlined with empty example values and transformer")
+            def test_outline():
+                pass
+            """
+        )
+    )
+    result = pytester.runpytest("-s")
+    result.assert_outcomes(passed=1)
+    assert collect_dumped_objects(result) == ["#", None, None]