test: fix invalid negative 1 value for uint64 test

Author: cpcloud

numba_cuda/numba/cuda/tests/cudapy/test_math.py

@@ -512,7 +512,7 @@ def test_math_fabs(self):
         self.unary_template_float32(math_fabs, np.fabs, start=-1)
         self.unary_template_float64(math_fabs, np.fabs, start=-1)
         self.unary_template_int64(math_fabs, np.fabs, start=-1)
-        self.unary_template_uint64(math_fabs, np.fabs, start=-1)
+        self.unary_template_uint64(math_fabs, np.fabs, start=0)
 
     # ---------------------------------------------------------------------------
     # test_math_gamma