feat: update lr_gradient to use config.ACTIVE_THEME

- Remove hardcoded GRAD_COLS and MSG_GRAD_COLS module constants
- Add _default_green_gradient() and _default_magenta_gradient() fallback functions
- Add _color_codes_to_ansi() to convert integer color codes from themes to ANSI escape strings
- Update lr_gradient() signature: cols parameter (was grad_cols)
- lr_gradient() now pulls colors from config.ACTIVE_THEME when available
- Falls back to default green gradient when no theme is active
- Existing calls with explicit cols parameter continue to work
- Add comprehensive tests for new functionality

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

tests/test_render.py

@@ -0,0 +1,174 @@
+"""
+Tests for engine.render module.
+"""
+
+import pytest
+
+from engine import config, render
+
+
+class TestDefaultGradients:
+    """Tests for default gradient fallback functions."""
+
+    def test_default_green_gradient_length(self):
+        """_default_green_gradient returns 12 colors."""
+        gradient = render._default_green_gradient()
+        assert len(gradient) == 12
+
+    def test_default_green_gradient_is_list(self):
+        """_default_green_gradient returns a list."""
+        gradient = render._default_green_gradient()
+        assert isinstance(gradient, list)
+
+    def test_default_green_gradient_all_strings(self):
+        """_default_green_gradient returns list of ANSI code strings."""
+        gradient = render._default_green_gradient()
+        assert all(isinstance(code, str) for code in gradient)
+
+    def test_default_magenta_gradient_length(self):
+        """_default_magenta_gradient returns 12 colors."""
+        gradient = render._default_magenta_gradient()
+        assert len(gradient) == 12
+
+    def test_default_magenta_gradient_is_list(self):
+        """_default_magenta_gradient returns a list."""
+        gradient = render._default_magenta_gradient()
+        assert isinstance(gradient, list)
+
+    def test_default_magenta_gradient_all_strings(self):
+        """_default_magenta_gradient returns list of ANSI code strings."""
+        gradient = render._default_magenta_gradient()
+        assert all(isinstance(code, str) for code in gradient)
+
+
+class TestLrGradientUsesActiveTheme:
+    """Tests for lr_gradient using active theme."""
+
+    def test_lr_gradient_uses_active_theme_when_cols_none(self):
+        """lr_gradient uses ACTIVE_THEME.main_gradient when cols=None."""
+        # Save original state
+        original_theme = config.ACTIVE_THEME
+
+        try:
+            # Set a theme
+            config.set_active_theme("green")
+
+            # Create simple test data
+            rows = ["text"]
+
+            # Call without cols parameter (cols=None)
+            result = render.lr_gradient(rows, offset=0.0)
+
+            # Should not raise and should return colored output
+            assert isinstance(result, list)
+            assert len(result) == 1
+            # Should have ANSI codes (no plain "text")
+            assert result[0] != "text"
+        finally:
+            # Restore original state
+            config.ACTIVE_THEME = original_theme
+
+    def test_lr_gradient_fallback_when_no_theme(self):
+        """lr_gradient uses fallback green when ACTIVE_THEME is None."""
+        # Save original state
+        original_theme = config.ACTIVE_THEME
+
+        try:
+            # Clear the theme
+            config.ACTIVE_THEME = None
+
+            # Create simple test data
+            rows = ["text"]
+
+            # Call without cols parameter (should use fallback)
+            result = render.lr_gradient(rows, offset=0.0)
+
+            # Should not raise and should return colored output
+            assert isinstance(result, list)
+            assert len(result) == 1
+            # Should have ANSI codes (no plain "text")
+            assert result[0] != "text"
+        finally:
+            # Restore original state
+            config.ACTIVE_THEME = original_theme
+
+    def test_lr_gradient_explicit_cols_parameter_still_works(self):
+        """lr_gradient with explicit cols parameter overrides theme."""
+        # Custom gradient
+        custom_cols = ["\033[38;5;1m", "\033[38;5;2m"] * 6
+
+        rows = ["xy"]
+        result = render.lr_gradient(rows, offset=0.0, cols=custom_cols)
+
+        # Should use the provided cols
+        assert isinstance(result, list)
+        assert len(result) == 1
+
+    def test_lr_gradient_respects_cols_parameter_name(self):
+        """lr_gradient accepts cols as keyword argument."""
+        custom_cols = ["\033[38;5;1m", "\033[38;5;2m"] * 6
+
+        rows = ["xy"]
+        # Call with cols as keyword
+        result = render.lr_gradient(rows, offset=0.0, cols=custom_cols)
+
+        assert isinstance(result, list)
+
+
+class TestLrGradientBasicFunctionality:
+    """Tests to ensure lr_gradient basic functionality still works."""
+
+    def test_lr_gradient_colors_non_space_chars(self):
+        """lr_gradient colors non-space characters."""
+        rows = ["hello"]
+
+        # Set a theme for the test
+        original_theme = config.ACTIVE_THEME
+        try:
+            config.set_active_theme("green")
+            result = render.lr_gradient(rows, offset=0.0)
+
+            # Result should have ANSI codes
+            assert any("\033[" in r for r in result), "Expected ANSI codes in result"
+        finally:
+            config.ACTIVE_THEME = original_theme
+
+    def test_lr_gradient_preserves_spaces(self):
+        """lr_gradient preserves spaces in output."""
+        rows = ["a b c"]
+
+        original_theme = config.ACTIVE_THEME
+        try:
+            config.set_active_theme("green")
+            result = render.lr_gradient(rows, offset=0.0)
+
+            # Spaces should be preserved (not colored)
+            assert " " in result[0]
+        finally:
+            config.ACTIVE_THEME = original_theme
+
+    def test_lr_gradient_empty_rows(self):
+        """lr_gradient handles empty rows correctly."""
+        rows = [""]
+
+        original_theme = config.ACTIVE_THEME
+        try:
+            config.set_active_theme("green")
+            result = render.lr_gradient(rows, offset=0.0)
+
+            assert result == [""]
+        finally:
+            config.ACTIVE_THEME = original_theme
+
+    def test_lr_gradient_multiple_rows(self):
+        """lr_gradient handles multiple rows."""
+        rows = ["row1", "row2", "row3"]
+
+        original_theme = config.ACTIVE_THEME
+        try:
+            config.set_active_theme("green")
+            result = render.lr_gradient(rows, offset=0.0)
+
+            assert len(result) == 3
+        finally:
+            config.ACTIVE_THEME = original_theme