From f7bf91410824e9090677943d51c46eed290bf736 Mon Sep 17 00:00:00 2001
From: Anthony Sottile <asottile@umich.edu>
Date: Sat, 1 Jun 2019 13:50:15 -0700
Subject: [PATCH] Fix `pytest.mark.parametrize` when the argvalue is an
 iterator

---
 changelog/5354.bugfix.rst      |  1 +
 src/_pytest/mark/structures.py | 10 +++++++---
 testing/test_mark.py           | 22 ++++++++++++++++++++++
 3 files changed, 30 insertions(+), 3 deletions(-)
 create mode 100644 changelog/5354.bugfix.rst

diff --git a/changelog/5354.bugfix.rst b/changelog/5354.bugfix.rst
new file mode 100644
index 00000000000..812ea8364aa
--- /dev/null
+++ b/changelog/5354.bugfix.rst
@@ -0,0 +1 @@
+Fix ``pytest.mark.parametrize`` when the argvalues is an iterator.
diff --git a/src/_pytest/mark/structures.py b/src/_pytest/mark/structures.py
index 561ccc3f45d..9602e8acfa3 100644
--- a/src/_pytest/mark/structures.py
+++ b/src/_pytest/mark/structures.py
@@ -113,14 +113,18 @@ def _parse_parametrize_args(argnames, argvalues, **_):
             force_tuple = len(argnames) == 1
         else:
             force_tuple = False
-        parameters = [
+        return argnames, force_tuple
+
+    @staticmethod
+    def _parse_parametrize_parameters(argvalues, force_tuple):
+        return [
             ParameterSet.extract_from(x, force_tuple=force_tuple) for x in argvalues
         ]
-        return argnames, parameters
 
     @classmethod
     def _for_parametrize(cls, argnames, argvalues, func, config, function_definition):
-        argnames, parameters = cls._parse_parametrize_args(argnames, argvalues)
+        argnames, force_tuple = cls._parse_parametrize_args(argnames, argvalues)
+        parameters = cls._parse_parametrize_parameters(argvalues, force_tuple)
         del argvalues
 
         if parameters:
diff --git a/testing/test_mark.py b/testing/test_mark.py
index 5bd97d547e8..dd9d352309d 100644
--- a/testing/test_mark.py
+++ b/testing/test_mark.py
@@ -413,6 +413,28 @@ def test_func(a, b):
     assert result.ret == 0
 
 
+def test_parametrize_iterator(testdir):
+    """parametrize should work with generators (#5354)."""
+    py_file = testdir.makepyfile(
+        """\
+        import pytest
+
+        def gen():
+            yield 1
+            yield 2
+            yield 3
+
+        @pytest.mark.parametrize('a', gen())
+        def test(a):
+            assert a >= 1
+        """
+    )
+    result = testdir.runpytest(py_file)
+    assert result.ret == 0
+    # should not skip any tests
+    result.stdout.fnmatch_lines(["*3 passed*"])
+
+
 class TestFunctional(object):
     def test_merging_markers_deep(self, testdir):
         # issue 199 - propagate markers into nested classes