fix: robustness

tests/test_coreg/test_workflows.py

@@ -320,3 +320,19 @@ def test_dem_coregistration(self) -> None:
                 estimated_initial_shift=test_shift_tuple,
                 random_state=42,
             )
+
+        # Check if the appropriate exception is raised with a wrong type initial shift
+        with pytest.raises(ValueError, match=r".*two numerical values.*"):
+            dem_coregistration(
+                tba_dem,
+                ref_dem,
+                estimated_initial_shift=["2", 2],
+                random_state=42,
+            )
+        with pytest.raises(ValueError, match=r".*two numerical values.*"):
+            dem_coregistration(
+                tba_dem,
+                ref_dem,
+                estimated_initial_shift=[2, 3, 5],
+                random_state=42,
+            )

xdem/coreg/workflows.py

@@ -227,6 +227,14 @@ def dem_coregistration(
 
     # Ensure that if an initial shift is provided, at least one coregistration method is affine.
     if estimated_initial_shift:
+        if not (
+            isinstance(estimated_initial_shift, (list, tuple))
+            and len(estimated_initial_shift) == 2
+            and all(isinstance(val, (float, int)) for val in estimated_initial_shift)
+        ):
+            raise ValueError(
+                "Argument `estimated_initial_shift` must be a list or tuple of exactly two numerical values."
+            )
         if isinstance(coreg_method, CoregPipeline):
             if not any(isinstance(step, AffineCoreg) for step in coreg_method.pipeline):
                 raise TypeError(