Fix step fixture injection

CHANGES.rst

@@ -3,6 +3,7 @@ Changelog
 
 Unreleased
 ----------
+- Fix an issue when only the first Step would inject a fixture, while later steps would not be able to.
 
 7.2.0
 ----------

src/pytest_bdd/compat.py

@@ -24,12 +24,17 @@ def inject_fixture(request: FixtureRequest, arg: str, value: Any) -> None:
         :param arg: argument name
         :param value: argument value
         """
-
+        # Ensure there's a fixture definition for the argument
         request._fixturemanager._register_fixture(
             name=arg,
             func=lambda: value,
             nodeid=request.node.nodeid,
         )
+        # Note the fixture we just registered will have a lower priority
+        # if there was already one registered, so we need to force its value
+        # to the one we want to inject.
+        fixture_def = request._get_active_fixturedef(arg)
+        fixture_def.cached_result = (value, None, None)
 
 else:
 

tests/steps/test_common.py

@@ -78,6 +78,48 @@ def _(bar, expected_value):
     assert bar == "test bar"
 
 
+def test_step_function_target_fixture_redefined(pytester):
+    pytester.makefile(
+        ".feature",
+        target_fixture=textwrap.dedent(
+            """\
+            Feature: Redefine a target fixture
+                Scenario: Redefine the target fixture after it has been injected once in the same scenario
+                    Given there is a foo with value "test foo"
+                    Then foo should be "test foo"
+                    Given there is a foo with value "test bar"
+                    Then foo should be "test bar"
+            """
+        ),
+    )
+    pytester.makepyfile(
+        textwrap.dedent(
+            """\
+        import pytest
+        from pytest_bdd import given, when, then, scenarios, parsers
+        from pytest_bdd.utils import dump_obj
+
+        scenarios("target_fixture.feature")
+
+        @given(parsers.parse('there is a foo with value "{value}"'), target_fixture="foo")
+        def _(value):
+            return value
+
+        @then(parsers.parse('foo should be "{expected_value}"'))
+        def _(foo, expected_value):
+            dump_obj(foo)
+            assert foo == expected_value
+        """
+        )
+    )
+    result = pytester.runpytest("-s")
+    result.assert_outcomes(passed=1)
+
+    [foo1, foo2] = collect_dumped_objects(result)
+    assert foo1 == "test foo"
+    assert foo2 == "test bar"
+
+
 def test_step_functions_same_parser(pytester):
     pytester.makefile(
         ".feature",