Add test for Lambdify of Piecewise

See: #234

Author: bjodah

symengine/tests/test_lambdify.py

@@ -76,6 +76,16 @@ def test_Lambdify():
                     [3*n+3, n**2, -1/(n+2), n*(n+1)*(n+2)])
 
 
+@unittest.skipUnless(have_numpy, "Numpy not installed")
+def test_Lambdify_Piecewise():
+    x = se.symbols('x')
+    p = se.Piecewise((-x, x<0), (x*x*x, True))
+    f = se.Lambdify([x], [p])
+    arr = np.linspace(3, 7)
+    assert np.all(f(-arr) == arr)
+    assert np.all(f(arr) == arr**3)
+
+
 @unittest.skipUnless(have_numpy, "Numpy not installed")
 def test_Lambdify_LLVM():
     n = 7