✨ (clockface): add implementation for SecondHand

Author: yuanyu90221

clockface/clockface.go

@@ -11,10 +11,18 @@ type Point struct {
 	Y float64
 }
 
+const secondHandLength = 90
+const clockCentreX = 150
+const clockCentreY = 150
+
 // SecondHand is the unit vector of the second hand of an analogue clock at time `t`
-// represented as a Point
+// represented as a Point.
 func SecondHand(t time.Time) Point {
-	return Point{150, 60}
+	p := secondHandPoint(t)
+	p = Point{p.X * secondHandLength, p.Y * secondHandLength}
+	p = Point{p.X, -p.Y}
+	p = Point{p.X + clockCentreX, p.Y + clockCentreY} //translate
+	return p
 }
 
 func secondsInRadians(t time.Time) float64 {

clockface/clockface_acceptance_test.go

@@ -18,13 +18,13 @@ func TestSecondHandAtMidnight(t *testing.T) {
 	}
 }
 
-// func TestSecondHandAt30Seconds(t *testing.T) {
-// 	tm := time.Date(1337, time.January, 1, 0, 0, 30, 0, time.UTC)
+func TestSecondHandAt30Seconds(t *testing.T) {
+	tm := time.Date(1337, time.January, 1, 0, 0, 30, 0, time.UTC)
 
-// 	want := clockface.Point{X: 150, Y: 150 + 90}
-// 	got := clockface.SecondHand(tm)
+	want := clockface.Point{X: 150, Y: 150 + 90}
+	got := clockface.SecondHand(tm)
 
-// 	if got != want {
-// 		t.Errorf("got %v, wanted %v", got, want)
-// 	}
-// }
+	if got != want {
+		t.Errorf("got %v, wanted %v", got, want)
+	}
+}