theme: Delete old themes.

Old theme format used in themes.py is deleted from this commit.

ZT_THEMES is changed to THEMES. `complete_and_incomplete_themes` is
edited to make it use the new THEMES instead of the old one.

The old theme completeness test is also removed.

Author: Rohitth007

tests/config/test_themes.py

@@ -16,63 +16,13 @@
     "gruvbox_dark",
     "zt_light",
     "zt_blue",
-    "gruvbox_dark24",
 }
 
 
 def test_all_themes():
     assert all_themes() == list(THEMES.keys())
 
 
-# Check built-in themes are complete for quality-control purposes
-@pytest.mark.parametrize(
-    "theme_name",
-    [
-        theme
-        if theme in expected_complete_themes
-        else pytest.param(theme, marks=pytest.mark.xfail(reason="incomplete"))
-        for theme in THEMES
-    ],
-)
-def test_builtin_theme_completeness(theme_name):
-    theme = THEMES[theme_name]
-    styles_in_theme = {style[0] for style in theme}
-
-    assert len(styles_in_theme) >= len(REQUIRED_STYLES)
-    assert all(required_style in styles_in_theme for required_style in REQUIRED_STYLES)
-
-
-@pytest.mark.parametrize(
-    "theme_name, depth",
-    [
-        ("zt_dark", 16),
-        ("zt_dark", 256),
-        ("zt_light", 16),
-        ("zt_blue", 16),
-        ("gruvbox_dark", 16),
-        ("gruvbox_dark", 256),
-        ("gruvbox_dark24", 2 ** 24),
-        ("gruvbox_dark24", 2 ** 24),
-    ],
-)
-def test_migrated_themes(theme_name, depth):
-    def split_and_strip(style):
-        style = style.split(",")
-        style = [s.strip() for s in style]
-        return style
-
-    old_theme = THEMES[theme_name]
-    new_theme = generate_theme(theme_name.replace("24", ""), depth)
-    for new_style, old_style in zip(new_theme, old_theme):
-        assert new_style[0] == old_style[0]
-        if depth == 16:
-            assert split_and_strip(new_style[1]) == split_and_strip(old_style[1])
-            assert split_and_strip(new_style[2]) == split_and_strip(old_style[2])
-        else:
-            assert split_and_strip(new_style[4]) == split_and_strip(old_style[4])
-            assert split_and_strip(new_style[5]) == split_and_strip(old_style[5])
-
-
 def test_complete_and_incomplete_themes():
     # These are sorted to ensure reproducibility
     result = (
@@ -128,7 +78,7 @@ class Color(Enum):
     ],
 )
 def test_generate_theme(mocker, color_depth, expected_urwid_theme):
-    mocker.patch.dict("zulipterminal.config.themes.ZT_THEMES", {"theme": theme})
+    mocker.patch.dict("zulipterminal.config.themes.THEMES", {"theme": theme})
     req_styles = {"s1": "", "s2": "bold"}
     mocker.patch.dict("zulipterminal.themes._template.REQUIRED_STYLES", req_styles)
     assert generate_theme("theme", color_depth) == expected_urwid_theme