Add tests

Author: isuruf

symengine/tests/test_cse.py

@@ -0,0 +1,17 @@
+from symengine import cse, sqrt, symbols
+
+def test_cse_single():
+    x, y, x0 = symbols("x, y, x0")
+    e = pow(x + y, 2) + sqrt(x + y)
+    substs, reduced = cse([e])
+    assert substs == [(x0, x + y)]
+    assert reduced == [sqrt(x0) + x0**2]
+
+
+def test_multiple_expressions():
+    w, x, y, z, x0 = symbols("w, x, y, z, x0")
+    e1 = (x + y)*z
+    e2 = (x + y)*w
+    substs, reduced = cse([e1, e2])
+    assert substs == [(x0, x + y)]
+    assert reduced == [x0*z, x0*w]