Draft: Add tests for run method

first attempt at tests for run

tests.py

@@ -28,6 +28,41 @@ def test_os_chdir(tmp_path):
     assert os.getcwd() == initial_cwd
 
 
+def test_run_method(tmp_path):
+    """Run tests for run method."""
+
+    run = mod.run
+
+    # test a command with options:
+    assert run(["date", "+%Y-%m-%d"]).returncode == 0
+    assert run("date +%Y-%m-%d", shell=True).returncode == 0
+
+    # tests interacting with the file system
+    with mod.os_chdir(str(tmp_path)):
+        # ensure single string command works
+        assert run(("ls -l"), shell=True).returncode == 0
+        # test spaces are handled correctly:
+        assert run(["touch", "file1", "file2"]).returncode == 0
+        assert os.path.exists("file1")
+        assert os.path.exists("file2")
+        # test output is captured:
+        assert (
+            b"Hello, world!\n"
+            in run(["echo", "Hello, world!"], capture_output=True).stdout
+        )
+
+    # check exceptions
+    with pytest.raises(FileNotFoundError):
+        run(["doesnotexistcommand"])
+
+    # check error code is checked
+    # 1. expect this to parse: return code is non-zero, but we don't check
+    run(["ls", "/doesnotexist"]),
+    # 2. expect this to fail:
+    with pytest.raises(subprocess.CalledProcessError):
+        run(["ls", "/doesnotexist"], check=True)
+
+
 def test_prepare_environment(tmp_path):
     """Simulate running preparation of environment.