[dtype] Change comments and solutions format for test

Author: Bertrand MICHEL

include/pybind11/numpy.h

@@ -507,12 +507,20 @@ class dtype : public object {
         return detail::array_descriptor_proxy(m_ptr)->names != nullptr;
     }
 
-    /// Single-character for dtype's kind (ex: float and double are 'f' or int and long int are 'i')
+    /**
+     * Single-character for dtype's kind
+     * ex: float and double are 'f' or int and long int are 'i',
+     *     i.e. "float and double" could be "floating point types",
+     *     and "int and long" could be "integral types")
+     */
     char kind() const {
         return detail::array_descriptor_proxy(m_ptr)->kind;
     }
 
-    /// Single-character for dtype's type (ex: float is 'f' and double 'd')
+    /** Single-character for dtype's type (ex: float is 'f' and double 'd').
+     *  NB: Following the Python API (i.e., dtype.char) is preferred here
+     *      rather than NumPy's internal C API (PyArray_Descr::type)
+     */
     char char_() const {
         return detail::array_descriptor_proxy(m_ptr)->type;
     }

tests/test_numpy_dtypes.cpp

@@ -267,7 +267,7 @@ py::list test_dtype_kind() {
     return list;
 }
 
-py::list test_dtype_type() {
+py::list test_dtype_char_() {
     py::list list;
     for (auto& dt : {
                      py::dtype("bool8"),   // bool
@@ -409,7 +409,7 @@ TEST_SUBMODULE(numpy_dtypes, m) {
     });
     m.def("test_dtype_ctors", &test_dtype_ctors);
     m.def("test_dtype_kind", &test_dtype_kind);
-    m.def("test_dtype_type", &test_dtype_type);
+    m.def("test_dtype_char_", &test_dtype_char_);
     m.def("test_dtype_methods", []() {
         py::list list;
         auto dt1 = py::dtype::of<int32_t>();

tests/test_numpy_dtypes.py

@@ -169,8 +169,8 @@ def test_dtype(simple_dtype):
         np.zeros(1, m.trailing_padding_dtype())
     )
 
-    assert m.test_dtype_kind() == ["b"] + ["i"] * 3 + ["f"] * 3
-    assert m.test_dtype_type() == ["?", "h", "i", "l", "f", "d", "g"]
+    assert m.test_dtype_kind() == list("biiifff")
+    assert m.test_dtype_char_() == list("?hilfdg")
 
 
 def test_recarray(simple_dtype, packed_dtype):