import junit.framework._
import org.junit.Assert._

class ArithExpTest extends TestCase {
  val Epsilon = 1.1e-16
  val zero = Const(0.)
  val negSeven = Const(-7.)
  val five = Const(5.)
  val negTen = Const(-10.)
  val ten = Const(10.)
  val twentyFive = Const(25.)
  
  val x = Var("x")
  val y = Var("y")
  val z = Var("z")
  
  /** Tests the eval() method in the ArithExpr composite. */
  def testExprPrint() {
    assertEquals("const 0.", "0.0", zero.exprString)
    assertEquals("const -7.", "-7.0", negSeven.exprString)
    assertEquals("const -10.", "-10.0", negTen.exprString)
    assertEquals("5 + 5",  "(5.0 + 5.0)", Sum(five, five).exprString);
    assertEquals("5 * 10", "(5.0 * 10.0)", Prod(five, ten).exprString);
    assertEquals("10/5", "(10.0 / 5.0)", Quot(ten, five).exprString);
    assertEquals("10 - 5", "(10.0 - 5.0)", Diff(ten, five).exprString);
    assertEquals("x * x", "(x * x)", Prod(x, x).exprString);
    assertEquals("y/z", "(y / z)", Quot(y, z).exprString);              
  }
  
  val e = EmptyEnv
  val env1 = e.cons("x", -10.).cons("y", 25.).cons("z", -5.)
  
    /** Tests the eval() method in the ArithExpr composite. */
  def testEval() {
    assertEquals("const 0.", 0., zero.eval(e), Epsilon)
    assertEquals("const 7.", -7., negSeven.eval(e), Epsilon)
    assertEquals("const -10.", -10., negTen.eval(e), Epsilon)
    assertEquals("25 + 5",  30., Sum(twentyFive, five).eval(e), Epsilon);
    assertEquals("-7 * 10", -70., Prod(negSeven, ten).eval(e), Epsilon);
    assertEquals("25/5", 5., Quot(twentyFive, five).eval(e), Epsilon);
    assertEquals("25 - 5", 20., Diff(twentyFive, five).eval(e), Epsilon);
    assertEquals("x * z", 50., Prod(x, z).eval(env1), Epsilon);
    assertEquals("x + y", 15., Sum(x, y).eval(env1), Epsilon)
    assertEquals("y/z", -5., Quot(y, z).eval(env1), Epsilon);              
  }
}