Add regression tests for goldstein edge handling

tests/test_filtering.py

@@ -4,6 +4,7 @@
 import pytest
 
 from dolphin import filtering, io
+from dolphin.goldstein import goldstein
 
 
 def test_filter_long_wavelength():
@@ -67,3 +68,56 @@ def test_filter(tmp_path, unw_files):
         max_workers=1,
         wavelength_cutoff=50,
     )
+
+
+class TestGoldstein:
+    def test_goldstein_non_multiple_dimensions(self):
+        """Test that edges are not zeroed when dimensions aren't multiples of psize."""
+        np.random.seed(42)
+        rows, cols = 100, 90  # Not multiples of psize=32
+        phase = np.random.rand(rows, cols) * 2 * np.pi - np.pi
+        complex_data = np.exp(1j * phase).astype(np.complex64)
+
+        result = goldstein(complex_data, alpha=0.5, psize=32)
+
+        assert result.shape == complex_data.shape
+        # Key regression test: edges should NOT be zero
+        assert not np.allclose(result[-5:, :], 0), "Bottom edge should not be zero"
+        assert not np.allclose(result[:, -5:], 0), "Right edge should not be zero"
+        assert not np.allclose(
+            result[-5:, -5:], 0
+        ), "Bottom-right corner should not be zero"
+
+    def test_goldstein_edge_normalization(self):
+        """Test that edge regions have similar magnitude to interior."""
+        np.random.seed(42)
+        rows, cols = 100, 90
+        phase = np.random.rand(rows, cols) * 2 * np.pi - np.pi
+        complex_data = np.exp(1j * phase).astype(np.complex64)
+
+        result = goldstein(complex_data, alpha=0.5, psize=32)
+
+        interior_mag = np.abs(result[40:60, 40:50]).mean()
+        edge_mag = np.abs(result[-10:, -10:]).mean()
+        ratio = edge_mag / interior_mag
+        # Edge magnitude should be within 10% of interior
+        assert 0.9 < ratio < 1.1, f"Edge/interior ratio {ratio:.3f} not close to 1"
+
+    def test_goldstein_preserves_zero_phase(self):
+        """Test that data with phase=0 is not incorrectly marked as empty."""
+        data = np.ones((64, 64), dtype=np.complex64)  # phase=0, magnitude=1
+        result = goldstein(data, alpha=0.5, psize=32)
+        # Should not be zeroed out
+        assert not np.allclose(
+            result, 0
+        ), "Valid data with phase=0 should not be zeroed"
+
+    def test_goldstein_small_array(self):
+        """Test that arrays smaller than psize still work."""
+        np.random.seed(42)
+        small_data = np.exp(1j * np.random.rand(20, 25) * 2 * np.pi).astype(
+            np.complex64
+        )
+        result = goldstein(small_data, alpha=0.5, psize=32)
+        assert result.shape == small_data.shape
+        assert not np.any(result == 0), "Small array should have no zeros"