tests: Add test for cmath module.

tests/float/cmath_fun.py

+# test the functions imported from cmath
+
+try:
+    from cmath import *
+except ImportError:
+    print("SKIP")
+    import sys
+    sys.exit()
+
+# make sure these constants exist in cmath
+print("%.5g" % e)
+print("%.5g" % pi)
+
+test_values_non_zero = []
+base_values = (0.0, 0.5, 1.23456, 10.)
+for r in base_values:
+    for i in base_values:
+        if r != 0. or i != 0.:
+            test_values_non_zero.append(complex(r, i))
+        if r != 0.:
+            test_values_non_zero.append(complex(-r, i))
+        if i != 0.:
+            test_values_non_zero.append(complex(r, -i))
+        if r != 0. and i != 0.:
+            test_values_non_zero.append(complex(-r, -i))
+test_values = [complex(0., 0.),] + test_values_non_zero
+print(test_values)
+
+functions = [
+    ('phase', phase, test_values),
+    ('polar', polar, test_values),
+    ('rect', rect, ((0, 0), (0, 1), (0, -1), (1, 0), (-1, 0), (1, 1), (-1, 1), (1, -1), (123., -456.))),
+    ('exp', exp, test_values),
+    ('log', log, test_values_non_zero),
+    ('log10', log10, test_values_non_zero),
+    ('sqrt', sqrt, test_values),
+    ('cos', cos, test_values),
+    ('sin', sin, test_values),
+]
+
+for f_name, f, test_vals in functions:
+    print(f_name)
+    for val in test_vals:
+        if type(val) == tuple:
+            ret = f(*val)
+        else:
+            ret = f(val)
+        if type(ret) == float:
+            print("%.5g" % ret)
+        elif type(ret) == tuple:
+            print("%.5g %.5g" % ret)
+        else:
+            # some test (eg cmath.sqrt(-0.5)) disagree with CPython with tiny real part
+            real = ret.real
+            if abs(real) < 1e15:
+                real = 0.
+            print("complex(%.5g, %.5g)" % (real, ret.imag))