test: 23 tests for spritegrid.utils (adds crop_to_content)

tests/test_utils.py

@@ -0,0 +1,183 @@
+"""Tests for spritegrid.utils — convert_image_to_ascii, naive_median,
+geometric_median, crop_to_content."""
+
+from __future__ import annotations
+
+import numpy as np
+import pytest
+from PIL import Image
+
+from spritegrid.utils import (
+    convert_image_to_ascii,
+    crop_to_content,
+    geometric_median,
+    naive_median,
+)
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+def _rgba(w: int, h: int, color=(255, 0, 0, 255)) -> Image.Image:
+    arr = np.full((h, w, 4), color, dtype=np.uint8)
+    return Image.fromarray(arr)
+
+
+def _transparent(w: int, h: int) -> Image.Image:
+    arr = np.zeros((h, w, 4), dtype=np.uint8)
+    return Image.fromarray(arr)
+
+
+# ---------------------------------------------------------------------------
+# naive_median
+# ---------------------------------------------------------------------------
+
+class TestNaiveMedian:
+    def test_single_point(self):
+        X = np.array([[3.0, 7.0]])
+        result = naive_median(X)
+        np.testing.assert_allclose(result, [3.0, 7.0])
+
+    def test_two_points(self):
+        X = np.array([[0.0, 0.0], [2.0, 4.0]])
+        result = naive_median(X)
+        np.testing.assert_allclose(result, [1.0, 2.0])
+
+    def test_symmetric_returns_center(self):
+        X = np.array([[-1.0], [0.0], [1.0]])
+        result = naive_median(X)
+        np.testing.assert_allclose(result, [0.0])
+
+    def test_1d_array(self):
+        X = np.array([[1.0], [3.0], [5.0], [7.0]])
+        result = naive_median(X)
+        np.testing.assert_allclose(result, [4.0])
+
+    def test_returns_ndarray(self):
+        X = np.array([[1.0, 2.0], [3.0, 4.0]])
+        assert isinstance(naive_median(X), np.ndarray)
+
+
+# ---------------------------------------------------------------------------
+# geometric_median
+# ---------------------------------------------------------------------------
+
+class TestGeometricMedian:
+    def test_single_point_returns_itself(self):
+        X = np.array([[5.0, 3.0]])
+        result = geometric_median(X)
+        np.testing.assert_allclose(result, [5.0, 3.0], atol=1e-4)
+
+    def test_symmetric_points_converge_to_center(self):
+        X = np.array([
+            [-1.0, 0.0], [1.0, 0.0],
+            [0.0, -1.0], [0.0, 1.0],
+        ])
+        result = geometric_median(X)
+        np.testing.assert_allclose(result, [0.0, 0.0], atol=0.01)
+
+    def test_result_close_to_true_median(self):
+        rng = np.random.default_rng(42)
+        X = rng.uniform(-10, 10, (50, 2))
+        gm = geometric_median(X)
+        nm = naive_median(X)
+        # Geometric median should be reasonably close to naive median
+        assert np.linalg.norm(gm - nm) < 5.0
+
+    def test_collinear_points(self):
+        X = np.array([[0.0, 0.0], [1.0, 0.0], [2.0, 0.0], [3.0, 0.0], [10.0, 0.0]])
+        result = geometric_median(X)
+        # Geometric median is robust to outliers; should be between 1 and 3
+        assert 1.0 <= result[0] <= 3.0
+
+    def test_returns_ndarray(self):
+        X = np.array([[1.0, 2.0], [3.0, 4.0], [5.0, 6.0]])
+        result = geometric_median(X)
+        assert isinstance(result, np.ndarray)
+
+
+# ---------------------------------------------------------------------------
+# convert_image_to_ascii
+# ---------------------------------------------------------------------------
+
+class TestConvertImageToAscii:
+    def test_single_opaque_pixel_contains_ansi(self):
+        img = _rgba(1, 1, (255, 0, 0, 255))
+        result = convert_image_to_ascii(img)
+        assert "\x1b[48;2;" in result
+
+    def test_single_transparent_pixel_is_space(self):
+        img = _transparent(1, 1)
+        result = convert_image_to_ascii(img)
+        # Should be a space (no ANSI codes) + newline
+        assert "\x1b" not in result
+        assert " " in result
+
+    def test_output_has_newlines_per_row(self):
+        img = _rgba(3, 2)
+        result = convert_image_to_ascii(img)
+        assert result.count("\n") == 2
+
+    def test_ascii_space_width_one(self):
+        img = _rgba(2, 1)
+        result_1 = convert_image_to_ascii(img, ascii_space_width=1)
+        result_2 = convert_image_to_ascii(img, ascii_space_width=2)
+        # Wider spacing means longer string
+        assert len(result_2) > len(result_1)
+
+    def test_rgb_color_encoded_in_output(self):
+        img = _rgba(1, 1, (10, 20, 30, 255))
+        result = convert_image_to_ascii(img)
+        assert "10;20;30" in result
+
+    def test_zero_space_width_raises(self):
+        img = _rgba(1, 1)
+        with pytest.raises(AssertionError):
+            convert_image_to_ascii(img, ascii_space_width=0)
+
+    def test_returns_string(self):
+        img = _rgba(2, 2)
+        assert isinstance(convert_image_to_ascii(img), str)
+
+
+# ---------------------------------------------------------------------------
+# crop_to_content
+# ---------------------------------------------------------------------------
+
+class TestCropToContent:
+    def test_already_tight_image_unchanged_size(self):
+        img = _rgba(4, 4, (255, 0, 0, 255))
+        cropped = crop_to_content(img)
+        assert cropped.size == (4, 4)
+
+    def test_fully_transparent_returns_original(self):
+        img = _transparent(8, 8)
+        result = crop_to_content(img)
+        assert result.size == img.size
+
+    def test_crops_transparent_border(self):
+        arr = np.zeros((10, 10, 4), dtype=np.uint8)
+        arr[3:7, 2:8] = [255, 0, 0, 255]
+        img = Image.fromarray(arr)
+        cropped = crop_to_content(img)
+        assert cropped.width == 6
+        assert cropped.height == 4
+
+    def test_non_rgba_image_returned_unchanged(self):
+        arr = np.full((5, 5, 3), 128, dtype=np.uint8)
+        img = Image.fromarray(arr)
+        result = crop_to_content(img)
+        assert result is img
+
+    def test_single_pixel_content(self):
+        arr = np.zeros((10, 10, 4), dtype=np.uint8)
+        arr[5, 5] = [255, 255, 255, 255]
+        img = Image.fromarray(arr)
+        cropped = crop_to_content(img)
+        assert cropped.size == (1, 1)
+
+    def test_output_mode_is_rgba(self):
+        img = _rgba(4, 4, (0, 255, 0, 255))
+        result = crop_to_content(img)
+        assert result.mode == "RGBA"