Implement datetime handling in pytest-bdd

- This was awful and convoluted

Co-authored-by: Micah Jerome Ellison <micah.jerome.ellison@gmail.com>

tests/unit/test_os_compat.py

@@ -0,0 +1,87 @@
+from unittest import mock
+import pytest
+
+from jrnl.os_compat import on_windows
+from jrnl.os_compat import on_posix
+from jrnl.os_compat import split_args
+
+
+@pytest.mark.parametrize(
+    "systems",
+    [
+        ["linux", False],
+        ["win32", True],
+        ["cygwin", False],
+        ["msys", False],
+        ["darwin", False],
+        ["os2", False],
+        ["os2emx", False],
+        ["riscos", False],
+        ["atheos", False],
+        ["freebsd7", False],
+        ["freebsd8", False],
+        ["freebsdN", False],
+        ["openbsd6", False],
+    ],
+)
+def test_on_windows(systems):
+    osname, expected_on_windows = systems[0], systems[1]
+    with mock.patch("jrnl.os_compat.platform", osname):
+        assert on_windows() == expected_on_windows
+
+
+@pytest.mark.parametrize(
+    "systems",
+    [
+        ["linux", True],
+        ["win32", False],
+        ["cygwin", True],
+        ["msys", True],
+        ["darwin", True],
+        ["os2", True],
+        ["os2emx", True],
+        ["riscos", True],
+        ["atheos", True],
+        ["freebsd7", True],
+        ["freebsd8", True],
+        ["freebsdN", True],
+        ["openbsd6", True],
+    ],
+)
+def test_on_posix(systems):
+    osname, expected_on_posix = systems[0], systems[1]
+    with mock.patch("jrnl.os_compat.platform", osname):
+        assert on_posix() == expected_on_posix
+
+
+@pytest.mark.parametrize(
+    "args",
+    [
+        ["notepad", ["notepad"]],
+        ["subl -w", ["subl", "-w"]],
+        [
+            '"C:\\Program Files\\Sublime Text 3\\subl.exe" -w',
+            ['"C:\\Program Files\\Sublime Text 3\\subl.exe"', "-w"],
+        ],
+    ],
+)
+def test_split_args_on_windows(args):
+    input_arguments, expected_split_args = args[0], args[1]
+    with mock.patch("jrnl.os_compat.on_windows", lambda: True):
+        assert split_args(input_arguments) == expected_split_args
+
+
+@pytest.mark.parametrize(
+    "args",
+    [
+        ["vim", ["vim"]],
+        [
+            'vim -f +Goyo +Limelight "+set spell linebreak"',
+            ["vim", "-f", "+Goyo", "+Limelight", '"+set spell linebreak"'],
+        ],
+    ],
+)
+def test_split_args_on_not_windows(args):
+    input_arguments, expected_split_args = args[0], args[1]
+    with mock.patch("jrnl.os_compat.on_windows", lambda: True):
+        assert split_args(input_arguments) == expected_split_args