Factor out graphviz into its own package

Makefile

@@ -8,24 +8,24 @@ assets:
 	mkdir -p assets
 
 assets/basic.svg: assets makesense
-	@MAKE -C testdata/basic -Bnd | ./makesense --type gv > assets/basic.svg
+	make -C testdata/basic -Bnd | ./bin/makesense --type gv > assets/basic.svg
 
 assets/c.svg: assets makesense
-	make -C testdata/c -Bnd | ./makesense --type gv > assets/c.svg
+	make -C testdata/c -Bnd | ./bin/makesense --type gv > assets/c.svg
 
 assets/basic.png: assets makesense
-	make -C testdata/basic -Bnd | ./makesense --type dot | dot -Tpng -o assets/basic.png
+	make -C testdata/basic -Bnd | ./bin/makesense --type dot | dot -Tpng -o assets/basic.png
 
 assets/c.png: assets makesense
-	make -C testdata/c -Bnd | ./makesense --type dot | dot -Tpng -o assets/c.png
+	make -C testdata/c -Bnd | ./bin/makesense --type dot | dot -Tpng -o assets/c.png
 
 assets/this.png: assets makesense
-	make -Bnd | ./makesense --type dot | dot -Tpng -o assets/this.png
+	make -Bnd | ./bin/makesense --type dot | dot -Tpng -o assets/this.png
 
 build: makesense
 
 makesense: makesense.go makesense_test.go
-	go build ./...
+	go build -o ./bin ./...
 
 test: makesense_test.go
 	go test ./...

go.mod

@@ -1,6 +1,6 @@
-module github.com/blevy/makesense
+module github.com/blevz/makesense
 
-go 1.15
+go 1.16
 
 require (
 	github.com/ajstarks/svgo v0.0.0-20200725142600-7a3c8b57fecb

graphutil/graph.go

@@ -0,0 +1,21 @@
+package graphutil
+
+import (
+	"bytes"
+
+	"github.com/goccy/go-graphviz"
+	"github.com/goccy/go-graphviz/cgraph"
+)
+
+var (
+	gv = graphviz.New()
+)
+
+func ToSvg(graph *cgraph.Graph, layoutType, renderFormat string) ([]byte, error) {
+	gv.SetLayout(graphviz.Layout(layoutType))
+	var buf bytes.Buffer
+	if err := gv.Render(graph, graphviz.Format(renderFormat), &buf); err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}

makesense.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"bufio"
-	"bytes"
 	"encoding/json"
 	"flag"
 	"fmt"
@@ -12,6 +11,8 @@ import (
 	"strings"
 
 	svg "github.com/ajstarks/svgo"
+	"github.com/blevz/makesense/graphutil"
+	_ "github.com/blevz/makesense/graphutil"
 	"github.com/goccy/go-graphviz"
 	"github.com/goccy/go-graphviz/cgraph"
 )
@@ -224,13 +225,11 @@ func (m MakesenseGraph) dumpGraphViz(w io.Writer) {
 			}
 		}
 	}
-	g.SetLayout(graphviz.Layout(*layoutType))
-	renderFormat := graphviz.Format(*renderType)
-	var buf bytes.Buffer
-	if err := g.Render(graph, renderFormat, &buf); err != nil {
+	b, err := graphutil.ToSvg(graph, *layoutType, *renderType)
+	if err != nil {
 		log.Fatal(err)
 	}
-	w.Write(buf.Bytes())
+	w.Write(b)
 }
 
 func (g MakesenseGraph) dumpList(w io.Writer) {

makesense.mk

@@ -6,7 +6,7 @@ all:: .makesense/make.svg
 	mkdir -p .makesense
 
 .makesense/make.svg: .makesense makesense
-	make -Bnd | ./makesense --type gv > .makesense/make.svg
+	make -Bnd | ./bin/makesense --type gv > .makesense/make.svg
 
 .makesense_clean:
 	rm -rf .makesense