Copy existing environment for usage in tests

tests/test_cli.py

@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+import os
+
 import pytest
 import sh
 
@@ -144,7 +146,9 @@ def test_run_with_existing_variable(tmp_path):
     with open(dotenv_file, "w") as f:
         f.write("a=b")
 
-    result = sh.dotenv("run", "printenv", "a", _env={"LANG": "en_US.UTF-8", "a": "c"})
+    test_env = dict(os.environ)
+    test_env.update({"a": "c"})
+    result = sh.dotenv("run", "printenv", "a", _env=test_env)
 
     assert result == "b\n"
 
@@ -155,12 +159,14 @@ def test_run_with_existing_variable_not_overridden(tmp_path):
     with open(dotenv_file, "w") as f:
         f.write("a=b")
 
+    test_env = dict(os.environ)
+    test_env.update({"LANG": "en_US.UTF-8", "a": "c"})
     result = sh.dotenv(
         "run",
         "--no-override",
         "printenv",
         "a",
-        _env={"LANG": "en_US.UTF-8", "a": "c"},
+        _env=test_env,
     )
 
     assert result == "c\n"
@@ -179,7 +185,7 @@ def test_run_with_none_value(tmp_path):
 
 def test_run_with_other_env(dotenv_file):
     with open(dotenv_file, "w") as f:
-        f.write("a=b")
+        f.write("LANG": "en_US.UTF-8", "a=b")
 
     result = sh.dotenv("--file", dotenv_file, "run", "printenv", "a")