simple test for testing truth of C values

tests/run/ctruthtests.pyx

+__doc__ = u"""
+>>> test_int(0)
+False
+>>> test_int(1)
+True
+
+>>> test_short(0)
+False
+>>> test_short(1)
+True
+
+>>> test_Py_ssize_t(0)
+False
+>>> test_Py_ssize_t(1)
+True
+
+>>> test_ptr()
+False
+>>> test_ptr2()
+2
+
+>>> test_attr_int(TestExtInt(0))
+False
+>>> test_attr_int(TestExtInt(1))
+True
+
+>>> test_attr_ptr(TestExtPtr(0))
+False
+>>> test_attr_ptr(TestExtPtr(1))
+True
+"""
+
+def test_ptr():
+    cdef void* p = NULL
+    if p:
+        return True
+    else:
+        return False
+
+def test_ptr2():
+    cdef void* p1 = NULL
+    cdef void* p2 = NULL
+    p1 += 1
+
+    if p1 and p2:
+        return 1
+    elif p1 or p2:
+        return 2
+    else:
+        return 3
+
+def test_int(int i):
+    if i:
+        return True
+    else:
+        return False
+
+def test_short(short i):
+    if i:
+        return True
+    else:
+        return False
+
+def test_Py_ssize_t(Py_ssize_t i):
+    if i:
+        return True
+    else:
+        return False
+
+cdef class TestExtInt:
+    cdef int i
+    def __init__(self, i): self.i = i
+
+def test_attr_int(TestExtInt e):
+    if e.i:
+        return True
+    else:
+        return False
+
+cdef class TestExtPtr:
+    cdef void* p
+    def __init__(self, int i): self.p = <void*>i
+
+def test_attr_ptr(TestExtPtr e):
+    if e.p:
+        return True
+    else:
+        return False