✨ (clockface): add implementation with for unit circle

Author: yuanyu90221

clockface/clockface.go

@@ -30,5 +30,9 @@ func testName(t time.Time) string {
 }
 
 func secondHandPoint(t time.Time) Point {
-	return Point{0, -1}
+	angle := secondsInRadians(t)
+	x := math.Sin(angle)
+	y := math.Cos(angle)
+
+	return Point{x, y}
 }

clockface/clockface_test.go

@@ -33,14 +33,25 @@ func TestSecondHandPoint(t *testing.T) {
 		point Point
 	}{
 		{simpleTime(0, 0, 30), Point{0, -1}},
+		{simpleTime(0, 0, 45), Point{-1, 0}},
 	}
 
 	for _, c := range cases {
 		t.Run(testName(c.time), func(t *testing.T) {
 			got := secondHandPoint(c.time)
-			if got != c.point {
+			if !roughlyEqualPoint(got, c.point) {
 				t.Fatalf("Wanted %v Point, but got %v", c.point, got)
 			}
 		})
 	}
 }
+
+func roughlyEqualFloat64(a, b float64) bool {
+	const equalityThreshold = 1e-7
+	return math.Abs(a-b) < equalityThreshold
+}
+
+func roughlyEqualPoint(a, b Point) bool {
+	return roughlyEqualFloat64(a.X, b.X) &&
+		roughlyEqualFloat64(a.Y, b.Y)
+}