feat: exposure detection (over/underexposed)

tests/test_analyzer.py

@@ -25,3 +25,22 @@ def test_normal_image_is_not_blurry(tmp_path):
     p = tmp_path / "sharp.jpg"
     img.save(p)
     assert is_blurry(str(p), threshold=100) is False
+
+
+from analyzer import is_overexposed, is_underexposed
+
+
+def test_white_image_is_overexposed(tmp_path):
+    path = make_test_image(tmp_path, color=(255, 255, 255))
+    assert is_overexposed(path, threshold=240) is True
+
+
+def test_dark_image_is_underexposed(tmp_path):
+    path = make_test_image(tmp_path, color=(10, 10, 10))
+    assert is_underexposed(path, threshold=30) is True
+
+
+def test_normal_image_is_neither(tmp_path):
+    path = make_test_image(tmp_path, color=(128, 128, 128))
+    assert is_overexposed(path, threshold=240) is False
+    assert is_underexposed(path, threshold=30) is False