def testXorAssign(self):
     vimcalc.parse("x = 5")
     vimcalc.parse("y = 3")
     assert vimcalc.parse("let x ^= y")  == "x = 6"
     vimcalc.parse("x = 2")
     vimcalc.parse("y = 10")
     assert vimcalc.parse("let x ^= y") == "x = 8"

 def testModAssign(self):
     vimcalc.parse("x = 4")
     vimcalc.parse("y = 5")
     assert vimcalc.parse("let x %= y") == "x = 4.0"
     vimcalc.parse("x = 4")
     vimcalc.parse("y = 5")
     assert vimcalc.parse("let y %= x") == "y = 1.0"

 def testChangeMode(self):
     vimcalc.parse(":dec")
     assert vimcalc.parse(":vars") == "VARIABLES:\n----------\n ans : 0\n e   : 2.71828182846\n phi : 1.61803398875\n pi  : 3.14159265359\n"
     vimcalc.parse(":hex")
     assert vimcalc.parse(":vars") == "VARIABLES:\n----------\n ans : 0x0\n e   : 0x2\n phi : 0x1\n pi  : 0x3\n"
     vimcalc.parse(":oct")
     assert vimcalc.parse(":vars") == "VARIABLES:\n----------\n ans : 0\n e   : 02\n phi : 01\n pi  : 03\n"

 def testParseError(self):
     assert vimcalc.parse("9**5/)")  == "Parse error: the expression is invalid."
     assert vimcalc.parse("4//5")    == "Parse error: the expression is invalid."
     assert vimcalc.parse("--1")     == "Parse error: the expression is invalid."
     assert vimcalc.parse("!4")      == "Parse error: the expression is invalid."
     assert vimcalc.parse("2***3")   == "Parse error: the expression is invalid."
     assert vimcalc.parse("sin(2,)") == "Parse error: apply() arg 2 expected sequence, found int"

 def testSubtraction(self):
     assert vimcalc.parse("4-3-2")   == "ans = -1.0"
     assert vimcalc.parse("(4-3)-2") == "ans = -1.0"
     assert vimcalc.parse("4-(3-2)") == "ans = 3.0"

 def testAddition(self):
     assert vimcalc.parse("(2+3)+4") == "ans = 9.0"
     assert vimcalc.parse("2+(3+4)") == "ans = 9.0"
     assert vimcalc.parse("2+3+4")   == "ans = 9.0"

 def testRightShift(self):
     assert vimcalc.parse("(16>>2)>>1") == "ans = 2"
     assert vimcalc.parse("16>>(2>>1)") == "ans = 8"
     assert vimcalc.parse("16>>1>>2")   == "ans = 2"

 def testModulo(self):
     assert vimcalc.parse("(5%4)%3") == "ans = 1.0"
     assert vimcalc.parse("5%(4%3)") == "ans = 0.0"
     assert vimcalc.parse("5%4%3")   == "ans = 1.0"

 def testMultiplication(self):
     assert vimcalc.parse("2*2*2")   == "ans = 8.0"
     assert vimcalc.parse("(2*2)*2") == "ans = 8.0"
     assert vimcalc.parse("2*(2*2)") == "ans = 8.0"

 def testComplicatedNested(self):
     assert vimcalc.parse("sin(sqrt(((pi/2)*2)**2)/2-(3-3))") == "ans = 1.0"

 def testPow(self):
     assert vimcalc.parse("pow(2,5)")      == "ans = 32.0", 'test pow(x,y)'

 def testPerms(self):
     assert vimcalc.parse("perms(3,2)")    == "ans = 6", 'test perms(n,k)'

 def testNrt(self):
     assert vimcalc.parse("nrt(27,3)")     == "ans = 3.0", 'test nrt(x,n)'

 def testMin(self):
     assert vimcalc.parse("min(3,7)")      == "ans = 3.0", 'test min(x,y)'
     assert vimcalc.parse("min(3.2,7.6)")  == "ans = 3.2", 'test min(x,y)'

 def testMax(self):
     assert vimcalc.parse("max(3,7)")      == "ans = 7.0", 'test max(x,y)'
     assert vimcalc.parse("max(3.2,7.6)")  == "ans = 7.6", 'test max(x,y)'

 def testFactorial(self):
     assert vimcalc.parse("5!") == "ans = 120", 'factorial'

 def runTest(self):
     assert vimcalc.parse("5*4") == "ans = 20.0", 'sanity check.'

 def testRad(self):
     assert vimcalc.parse("rad(0)")        == "ans = 0.0", 'test rad(x)'
     assert vimcalc.parse("rad(180)")      == "ans = 3.14159265359", 'test rad(x)'
     assert vimcalc.parse("rad(360)")      == "ans = 6.28318530718", 'test rad(x)'

 def testAllPrecedenceAtOnce(self):
     assert vimcalc.parse("5*4+2/sin(pi/2)**2+-1") == "ans = 21.0"

 def testRound(self):
     assert vimcalc.parse("round(4.2)")    == "ans = 4.0", 'test round(x)'
     assert vimcalc.parse("round(4.7)")    == "ans = 5.0", 'test round(x)'