gear1_check_test.go

package gear1_test

import (
	"go-poodr/chapter9/gear1"
	. "launchpad.net/gocheck"
	"math"
	"testing"
)

// Hook up gocheck into the gotest runner.
func Test(t *testing.T) { TestingT(t) }

type MySuite struct{}

var _ = Suite(&MySuite{})

func (s *MySuite) TestCalculatesDiameter(c *C) {
	wheel := gear1.NewWheel(26, 1.5)
	c.Assert(wheel.Diameter(), Within, 0.01, 29.0)
}

func (s *MySuite) TestCalculatesGearInches(c *C) {
	gear := gear1.NewGear(52, 11, 26, 1.5)
	c.Assert(gear.GearInches(), Within, 0.01, 137.1)
}

/*
  Within Delta Custom Checker
  Would be nice if gocheck included something like this.
*/
type withinChecker struct {
	*CheckerInfo
}

var Within Checker = &withinChecker{
	&CheckerInfo{Name: "Within", Params: []string{"obtained", "delta", "expected"}},
}

func (c *withinChecker) Check(params []interface{}, names []string) (result bool, error string) {
	obtained, ok := params[0].(float64)
	if !ok {
		return false, "obtained must be a float64"
	}
	delta, ok := params[1].(float64)
	if !ok {
		return false, "delta must be a float64"
	}
	expected, ok := params[2].(float64)
	if !ok {
		return false, "expected must be a float64"
	}
	return math.Abs(obtained-expected) <= delta, ""
}