clockface: add minute hand tests

clockface/clockface.go

@@ -14,6 +14,7 @@ type Point struct {
 }
 
 const (
+	minuteHandLength = 80
 	secondHandLength = 90
 	clockCentreX     = 150
 	clockCentreY     = 150
@@ -34,12 +35,13 @@ const svgEnd = `</svg>`
 func SVGWriter(w io.Writer, t time.Time) {
 	io.WriteString(w, svgStart)
 	io.WriteString(w, bezel)
-	SecondHand(w, t)
+	secondHand(w, t)
+	minuteHand(w, t)
 	io.WriteString(w, svgEnd)
 }
 
 // SecondHand is the unit vector of the second hand of an analogue clock at the time `t` represented as a Point
-func SecondHand(w io.Writer, t time.Time) {
+func secondHand(w io.Writer, t time.Time) {
 	p := secondHandPoint(t)
 	p = Point{p.X * secondHandLength, p.Y * secondHandLength} // scale
 	p = Point{p.X, -p.Y}                                      // flip
@@ -52,30 +54,39 @@ func SecondHand(w io.Writer, t time.Time) {
 	)
 }
 
+// MinuteHand is the unit vector of the minute hand of an analogue clock at the time `t` represented as a Point
+func minuteHand(w io.Writer, t time.Time) {
+	p := minuteHandPoint(t)
+	p = Point{p.X * minuteHandLength, p.Y * minuteHandLength} // scale
+	p = Point{p.X, -p.Y}                                      // flip
+	p = Point{p.X + clockCentreX, p.Y + clockCentreY}         // translate
+	fmt.Fprintf(
+		w,
+		`<line x1="150" y1="150" x2="%f" y2="%f" style="fill:none;stroke:#f00;stroke-width:3px;"/>`,
+		p.X,
+		p.Y,
+	)
+}
+
 func minutesInRadians(t time.Time) float64 {
 	return (secondsInRadians(t) / 60) + math.Pi/(30/float64(t.Minute()))
 }
 
 func minuteHandPoint(t time.Time) Point {
-	angle := minutesInRadians(t)
-	x := math.Sin(angle)
-	y := math.Cos(angle)
-
-	return Point{x, y}
+	return angleToPoint(minutesInRadians(t))
 }
 
 func secondsInRadians(t time.Time) float64 {
-	// XXX:Wanted 3.141592653589793 radians, but got 3.1415926535897936
-	// return float64(t.Second()) * (math.Pi / 30)
-
 	return math.Pi / (30 / float64(t.Second()))
 }
 
 func secondHandPoint(t time.Time) Point {
-	angle := secondsInRadians(t)
+	return angleToPoint(secondsInRadians(t))
+}
+
+func angleToPoint(angle float64) Point {
 	x := math.Sin(angle)
 	y := math.Cos(angle)
 
-	// XXX: Wanted {0 -1} Point, but got {1.2246467991473515e-16 -1}
 	return Point{x, y}
 }

clockface/clockface_acceptance_test.go

@@ -59,6 +59,34 @@ func TestSVGWriterSecondHand(t *testing.T) {
 	}
 }
 
+func TestSVGWriterMinuteHand(t *testing.T) {
+	cases := []struct {
+		time time.Time
+		line Line
+	}{
+		{simpleTime(0, 0, 0), Line{150, 150, 150, 70}},
+		// {simpleTime(0, 0, 30), Line{150, 150, 150, 240}},
+	}
+
+	for _, c := range cases {
+		t.Run(testName(c.time), func(t *testing.T) {
+			b := bytes.Buffer{}
+			SVGWriter(&b, c.time)
+
+			svg := Svg{}
+			xml.Unmarshal(b.Bytes(), &svg)
+
+			if !containsLine(c.line, svg.Line) {
+				t.Errorf(
+					"Expected to find the minute hand line %+v in the SVG lines %v",
+					c.line,
+					svg.Line,
+				)
+			}
+		})
+	}
+}
+
 func containsLine(l Line, ls []Line) bool {
 	for _, line := range ls {
 		if line == l {