Delete unnecessary check and add new test with assertions

cpp/splinepy/py/py_spline.hpp

@@ -165,13 +165,6 @@ class PySpline {
         for (py::handle k : kv) {
           this_knot = k.cast<double>();
 
-          // can't be negative
-          if (this_knot < 0) {
-            splinepy::utils::PrintAndThrowError("Parametric dimension (",
-                                                kv_dim,
-                                                ")",
-                                                "includes negative knot.");
-          }
           // must be increasing
           if (prev_knot - this_knot > 0) {
             splinepy::utils::PrintAndThrowError(
@@ -204,6 +197,9 @@ class PySpline {
               nknots,
               "were given.");
         }
+
+        // Only use closed knot-vectors
+
         // multiply expected control mesh resolution
         required_ncps *= nknots - degrees_ptr[kv_dim] - 1;
 

tests/test_spline_constructors.py

@@ -0,0 +1,26 @@
+try:
+    from . import common as c
+except BaseException:
+    import common as c
+
+
+class TestSplineConstructors(c.unittest.TestCase):
+    """Perform checks and see if spline data is coherent"""
+
+    def testBSplines(self):
+        """
+        Perform checks on BSpline class
+        """
+        self.assertRaisesRegex(
+            RuntimeError,
+            "SPLINEPY ERROR - Invalid number of control points. 2 exepcted, "
+            "but 0 were given.",
+            c.splinepy.BSpline,
+            degrees=[1],
+            knot_vectors=[[0, 0, 1, 1]],
+            control_points=c.np.ones((0, 0)),
+        )
+
+
+if __name__ == "__main__":
+    c.unittest.main()