add test for field types

tests/jit/test_cpujit.py

+import pytest
+
 import sympy as sp
 import numpy as np
 from pystencils import create_kernel, Assignment, fields
 from pystencils.jit import CpuJit
 
 
-def test_basic_cpu_kernel(tmp_path):
-    jit = CpuJit.create(objcache=tmp_path)
+@pytest.fixture
+def cpu_jit(tmp_path) -> CpuJit:
+    return CpuJit.create(objcache=tmp_path)
+
 
+def test_basic_cpu_kernel(cpu_jit):
     f, g = fields("f, g: [2D]")
     asm = Assignment(f.center(), 2.0 * g.center())
     ker = create_kernel(asm)
-    kfunc = jit.compile(ker)
+    kfunc = cpu_jit.compile(ker)
 
     rng = np.random.default_rng()
     f_arr = rng.random(size=(34, 26), dtype="float64")
@@ -19,3 +24,27 @@ def test_basic_cpu_kernel(tmp_path):
     kfunc(f=f_arr, g=g_arr)
 
     np.testing.assert_almost_equal(g_arr, 2.0 * f_arr)
+
+
+def test_argument_type_error(cpu_jit):
+    f, g = fields("f, g: [2D]")
+    c = sp.Symbol("c")
+    asm = Assignment(f.center(), c * g.center())
+    ker = create_kernel(asm)
+    kfunc = cpu_jit.compile(ker)
+
+    arr_fp16 = np.zeros((23, 12), dtype="float16")
+    arr_fp32 = np.zeros((23, 12), dtype="float32")
+    arr_fp64 = np.zeros((23, 12), dtype="float64")
+
+    with pytest.raises(TypeError):
+        kfunc(f=arr_fp32, g=arr_fp64, c=2.0)
+
+    with pytest.raises(TypeError):
+        kfunc(f=arr_fp64, g=arr_fp32, c=2.0)
+
+    with pytest.raises(TypeError):
+        kfunc(f=arr_fp16, g=arr_fp16, c=2.0)
+
+    #   Wrong scalar types are OK, though
+    kfunc(f=arr_fp64, g=arr_fp64, c=np.float16(1.0))