themes/run: Enable transparency via generate_theme & parse_themefile.

This is connected through to run.py, but is disabled pending
config-file/CLI infrastructure.

Tests updated.

Author: neiljp

tests/config/test_themes.py

@@ -202,7 +202,9 @@ class FakeTheme:
 
     mocker.patch(MODULE + ".THEMES", {fake_theme_name: FakeTheme})
 
-    generated_theme = generate_theme(fake_theme_name, depth)
+    generated_theme = generate_theme(
+        fake_theme_name, color_depth=depth, transparent_background=False
+    )
 
     assert len(generated_theme) == len(theme_styles) + expected_pygments_length
     assert (single_style, "", "", "", "a", "b") in generated_theme
@@ -219,9 +221,11 @@ class FakeTheme:
 
     mocker.patch(MODULE + ".THEMES", {fake_theme_name: FakeTheme})
 
+    kwargs: Dict[str, Any] = dict(color_depth=depth, transparent_background=False)
+
     # No attributes (STYLES or META) - flag missing Color
     with pytest.raises(MissingThemeAttributeError) as e:
-        generate_theme(fake_theme_name, depth)
+        generate_theme(fake_theme_name, **kwargs)
     assert str(e.value) == "Theme is missing required attribute 'Color'"
 
     # Color but missing STYLES - flag missing STYLES
@@ -232,7 +236,7 @@ class FakeColor(Enum):
     FakeTheme.Color = FakeColor  # type: ignore [attr-defined]
 
     with pytest.raises(MissingThemeAttributeError) as e:
-        generate_theme(fake_theme_name, depth)
+        generate_theme(fake_theme_name, **kwargs)
     assert str(e.value) == "Theme is missing required attribute 'STYLES'"
 
     # Color, STYLES and META, but no pygments data in META
@@ -241,7 +245,7 @@ class FakeColor(Enum):
     FakeTheme.META = {}  # type: ignore [attr-defined]
 
     with pytest.raises(MissingThemeAttributeError) as e:
-        generate_theme(fake_theme_name, depth)
+        generate_theme(fake_theme_name, **kwargs)
     assert str(e.value) == """Theme is missing required attribute 'META["pygments"]'"""
 
     # Color, STYLES and META, but incomplete pygments in META
@@ -250,7 +254,7 @@ class FakeColor(Enum):
     }
 
     with pytest.raises(MissingThemeAttributeError) as e:
-        generate_theme(fake_theme_name, depth)
+        generate_theme(fake_theme_name, **kwargs)
     assert (
         str(e.value)
         == """Theme is missing required attribute 'META["pygments"]["overrides"]'"""
@@ -306,7 +310,7 @@ class Color(Enum):
     req_styles = {"s1": "", "s2": "bold"}
     mocker.patch.dict("zulipterminal.config.themes.REQUIRED_STYLES", req_styles)
     assert (
-        parse_themefile(theme_styles, color_depth, Color.DARK_MAGENTA)
+        parse_themefile(theme_styles, color_depth, Color.DARK_MAGENTA, False)
         == expected_urwid_theme
     )
 

tests/core/test_core.py

@@ -44,7 +44,9 @@ def controller(self, mocker: MockerFixture) -> Controller:
 
         self.config_file = "path/to/zuliprc"
         self.theme_name = "zt_dark"
-        self.theme = generate_theme("zt_dark", 256)
+        self.theme = generate_theme(
+            "zt_dark", color_depth=256, transparent_background=False
+        )
         self.in_explore_mode = False
         self.autohide = True  # FIXME Add tests for no-autohide
         self.notify_enabled = False

zulipterminal/cli/run.py

@@ -559,7 +559,11 @@ def print_setting(setting: str, data: SettingData, suffix: str = "") -> None:
         color_depth_str = zterm["color-depth"].value
         color_depth = COLOR_DEPTH_ARGS_TO_DEPTHS[color_depth_str]
 
-        theme_data = generate_theme(theme_to_use.value, color_depth)
+        theme_data = generate_theme(
+            theme_to_use.value,
+            color_depth=color_depth,
+            transparent_background=False,
+        )
 
         # Translate valid strings for boolean values into True/False
         boolean_settings: Dict[str, bool] = dict()

zulipterminal/config/themes.py

@@ -173,8 +173,13 @@ def complete_and_incomplete_themes() -> Tuple[List[str], List[str]]:
     return sorted(complete), sorted(incomplete)
 
 
-def generate_theme(theme_name: str, color_depth: int) -> ThemeSpec:
-    theme_module = THEMES[theme_name]
+def generate_theme(
+    name: str,
+    *,
+    color_depth: int,
+    transparent_background: bool,
+) -> ThemeSpec:
+    theme_module = THEMES[name]
 
     try:
         theme_colors = theme_module.Color
@@ -205,7 +210,12 @@ def generate_theme(theme_name: str, color_depth: int) -> ThemeSpec:
         background_color = Background.COLOR
         pygments_styles = []
 
-    urwid_theme = parse_themefile(theme_styles, color_depth, background_color)
+    urwid_theme = parse_themefile(
+        theme_styles,
+        color_depth,
+        background_color,
+        transparent_background,
+    )
     urwid_theme.extend(pygments_styles)
 
     return urwid_theme
@@ -240,13 +250,15 @@ def parse_themefile(
     theme_styles: Dict[Optional[str], Tuple[Any, Any]],
     color_depth: int,
     background_color: Any,
+    transparent_background: bool,
 ) -> ThemeSpec:
     urwid_theme = []
     for style_name, (fg_name, bg_name) in theme_styles.items():
         fg_code16, fg_code256, fg_code24, *fg_props = fg_name.value.split()
 
-        # If background (bg) is specific enum, use specified background_color instead
-        if bg_name == Background.COLOR:
+        # Background.COLOR is transparent
+        # => Replace with background_color, unless transparency is requested
+        if bg_name == Background.COLOR and not transparent_background:
             bg_name = background_color  # noqa: PLW2901  # overwrite loop variable
 
         bg_code16, bg_code256, bg_code24, *bg_props = bg_name.value.split()