✨ (clockface): create SVGWriter and implemented it

Author: yuanyu90221

clockface_sample/clock.svg

@@ -1,12 +1,41 @@
 package clockface_test
 
 import (
+	"strings"
 	"testing"
 	"time"
 
 	clockface "github.com/leetcode-golang-classroom/learn-golang-with-tests/clockface_sample/clockface"
 )
 
+func TestSVGWriterAtMidnight(t *testing.T) {
+	tm := time.Date(1337, time.January, 1, 0, 0, 0, 0, time.UTC)
+
+	var b strings.Builder
+	clockface.SVGWriter(&b, tm)
+	got := b.String()
+
+	want := `<line x1="150" y1="150" x2="150.000" y2="60.000"`
+
+	if !strings.Contains(got, want) {
+		t.Errorf("Expected to find the second hand %v, in the SVG output %v", want, got)
+	}
+}
+
+func TestSVGWriterAt30Seconds(t *testing.T) {
+	tm := time.Date(1337, time.January, 1, 0, 0, 30, 0, time.UTC)
+
+	var b strings.Builder
+	clockface.SVGWriter(&b, tm)
+	got := b.String()
+
+	want := `<line x1="150" y1="150" x2="150.000" y2="240.000"`
+
+	if !strings.Contains(got, want) {
+		t.Errorf("Expected to find the second hand %v, in the SVG output %v", want, got)
+	}
+}
+
 func TestSecondHandAtMidnight(t *testing.T) {
 	tm := time.Date(1337, time.January, 1, 0, 0, 0, 0, time.UTC)
 

clockface_sample/clockface/clockface_acceptance_test.go

@@ -0,0 +1,35 @@
+package clockface
+
+import (
+	"fmt"
+	"io"
+	"time"
+)
+
+// SVGWriter writes an SVG representation of an analogue clock, showing the time t, to the writer w.
+func SVGWriter(w io.Writer, t time.Time) {
+	io.WriteString(w, svgStart)
+	io.WriteString(w, bezel)
+	secondHand(w, t)
+	io.WriteString(w, svgEnd)
+}
+
+func secondHand(w io.Writer, t time.Time) {
+	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
+	fmt.Fprintf(w, `<line x1="150" y1="150" x2="%.3f" y2="%.3f" style="fill:none;stroke:#f00;stroke-width:3px;"/>`, p.X, p.Y)
+}
+
+const svgStart = `<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<svg xmlns="http://www.w3.org/2000/svg"
+     width="100%"
+     height="100%"
+     viewBox="0 0 300 300"
+     version="2.0">`
+
+const bezel = `<circle cx="150" cy="150" r="100" style="fill:#fff;stroke:#000;stroke-width:5px;"/>`
+
+const svgEnd = `</svg>`

clockface_sample/clockface/svgWriter.go

@@ -1,8 +1,6 @@
 package main
 
 import (
-	"fmt"
-	"io"
 	"os"
 	"time"
 
@@ -11,25 +9,5 @@ import (
 
 func main() {
 	t := time.Now()
-	sh := clockface.SecondHand(t)
-	io.WriteString(os.Stdout, svgStart)
-	io.WriteString(os.Stdout, bezel)
-	io.WriteString(os.Stdout, secondHandTag(sh))
-	io.WriteString(os.Stdout, svgEnd)
+	clockface.SVGWriter(os.Stdout, t)
 }
-
-func secondHandTag(p clockface.Point) string {
-	return fmt.Sprintf(`<line x1="150" y1="150" x2="%f" y2="%f" style="fill:none;stroke:#f00;stroke-width:3px;"/>`, p.X, p.Y)
-}
-
-const svgStart = `<?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
-<svg xmlns="http://www.w3.org/2000/svg"
-     width="100%"
-     height="100%"
-     viewBox="0 0 300 300"
-     version="2.0">`
-
-const bezel = `<circle cx="150" cy="150" r="100" style="fill:#fff;stroke:#000;stroke-width:5px;"/>`
-
-const svgEnd = `</svg>`