Make it easier to add new envfile tests

We have 2 tests using the valid yaml. Both test need to create fake
addons directories in a temporary directory. This makes it harder than
needed to create new tests.

Change the valid_yaml to pytest fixture returning an Env namedtuple with
an open file object with the valid yaml and the path of the addons
directory created by the fixture. With this creating new test requires
one line to create an env.

Signed-off-by: Nir Soffer <nsoffer@redhat.com>

test/drenv/envfile_test.py

@@ -3,9 +3,16 @@
 
 import io
 import pytest
+from collections import namedtuple
+
 from . import envfile
 
-valid_yaml = """
+Env = namedtuple("Env", "file,addons_root")
+
+
+@pytest.fixture
+def valid_env(tmpdir):
+    yaml = """
 name: test
 
 templates:
@@ -57,17 +64,14 @@
         args: []
 """
 
-
-def create_addons(tmpdir):
     for i in range(1, 7):
         tmpdir.mkdir(f"addon{i}")
 
+    return Env(file=io.StringIO(yaml), addons_root=str(tmpdir))
 
 
-def test_valid(tmpdir):
-    create_addons(tmpdir)
-    f = io.StringIO(valid_yaml)
-    env = envfile.load(f, addons_root=str(tmpdir))
+def test_valid(valid_env):
+    env = envfile.load(valid_env.file, addons_root=valid_env.addons_root)
 
     # profile dr1
 
@@ -122,10 +126,12 @@ def test_valid(tmpdir):
     assert worker["addons"][0]["args"] == []
 
 
-def test_name_prefix(tmpdir):
-    create_addons(tmpdir)
-    f = io.StringIO(valid_yaml)
-    env = envfile.load(f, name_prefix="prefix-", addons_root=str(tmpdir))
+def test_name_prefix(valid_env):
+    env = envfile.load(
+        valid_env.file,
+        name_prefix="prefix-",
+        addons_root=valid_env.addons_root,
+    )
 
     # env