rounder_test.go

package polygol

import (
	"testing"
)

func TestRounderRound(t *testing.T) {
	t.Parallel()

	var pt1, pt2, pt3 *point

	rounder := newPtRounder()

	// no overlap
	t.Run("no-overlap", func(t *testing.T) {
		rounder.reset()
		pt1 = &point{x: 3, y: 4}
		pt2 = &point{x: 4, y: 5}
		pt3 = &point{x: 5, y: 5}
		expect(t, rounder.round(pt1.x, pt1.y).equal(*pt1))
		expect(t, rounder.round(pt2.x, pt2.y).equal(*pt2))
		expect(t, rounder.round(pt3.x, pt3.y).equal(*pt3))
	})

	// exact overlap
	t.Run("exact-overlap", func(t *testing.T) {
		rounder.reset()
		pt1 = &point{x: 3, y: 4}
		pt2 = &point{x: 4, y: 5}
		pt3 = &point{x: 3, y: 4}
		expect(t, rounder.round(pt1.x, pt1.y).equal(*pt1))
		expect(t, rounder.round(pt2.x, pt2.y).equal(*pt2))
		expect(t, rounder.round(pt3.x, pt3.y).equal(*pt3))
	})

	// rounding one coordinate
	t.Run("rounding-one-coordinate", func(t *testing.T) {
		rounder.reset()
		pt1 = &point{x: 3, y: 4}
		pt2 = &point{x: 3 + epsilon, y: 4}
		pt3 = &point{x: 3, y: 4 + epsilon}
		expect(t, rounder.round(pt1.x, pt1.y).equal(*pt1))
		expect(t, rounder.round(pt2.x, pt2.y).equal(*pt1))
		expect(t, rounder.round(pt3.x, pt3.y).equal(*pt1))
	})

	// rounding both coordinates
	t.Run("rounding-both-coordinates", func(t *testing.T) {
		rounder.reset()
		pt1 = &point{x: 3, y: 4}
		pt2 = &point{x: 3 + epsilon, y: 4 + epsilon}
		expect(t, rounder.round(pt1.x, pt1.y).equal(*pt1))
		expect(t, rounder.round(pt2.x, pt2.y).equal(*pt1))
	})

	// preseed with 0
	t.Run("preseed-with-zero", func(t *testing.T) {
		rounder.reset()
		pt1 = &point{x: epsilon / 2, y: -epsilon / 2}
		expect(t, pt1.x != 0)
		expect(t, pt1.y != 0)
		expect(t, rounder.round(pt1.x, pt1.y).equal(point{x: 0, y: 0}))
	})
}