Add tiny go.mod parser instead of third party package.

cmd/goa/gen.go

@@ -1,9 +1,11 @@
 package main
 
 import (
+	"bufio"
 	"fmt"
 	"go/parser"
 	"go/token"
+	"io"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -13,7 +15,6 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/sirkon/goproxy/gomod"
 	"goa.design/goa/v3/codegen"
 	"golang.org/x/tools/go/packages"
 )
@@ -162,26 +163,32 @@ func (g *Generator) goaPackage() (string, error) {
 		return goaPkg, nil
 	}
 	goaPkg = fmt.Sprintf("goa.design/goa/v%d", g.DesignVersion)
-	gomod := findGoMod()
-	if _, err := os.Stat(gomod); err != nil {
+	path := findGoMod()
+	if _, err := os.Stat(path); err != nil {
 		return goaPkg, nil
 	}
-	b, err := ioutil.ReadFile(gomod)
+	fp, err := os.Open(path)
 	if err != nil {
-		return "", fmt.Errorf("read go.mod error, %v", err)
+		return "", err
 	}
-	return parseGoModGoaPackage(goaPkg, b)
+	defer fp.Close()
+	return parseGoModGoaPackage(goaPkg, fp)
 }
 
-func parseGoModGoaPackage(goaPkg string, b []byte) (string, error) {
-	mod, err := gomod.Parse("go.mod", b)
-	if err != nil {
-		return "", fmt.Errorf("read go.mod error, %v", err)
+var reMod = regexp.MustCompile(`(goa\.design/goa/v\d+?)\s+(\S+?)\s*$`)
+
+func parseGoModGoaPackage(pkg string, r io.Reader) (string, error) {
+	s := bufio.NewScanner(r)
+	for s.Scan() {
+		match := reMod.FindStringSubmatch(s.Text())
+		if len(match) == 3 && match[1] == pkg {
+			return match[1] + "@" + match[2], nil
+		}
 	}
-	if v, ok := mod.Require[goaPkg]; ok {
-		return goaPkg + "@" + v, nil
+	if err := s.Err(); err != nil {
+		return "", fmt.Errorf("scan error, %v", err)
 	}
-	return goaPkg, nil
+	return pkg, nil
 }
 
 // Compile compiles the generator.

cmd/goa/gen_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"strings"
 	"testing"
 )
 
@@ -37,20 +38,67 @@ func TestGenerator_goaPackage(t *testing.T) {
 }
 
 func TestParseGoModGoaPackage(t *testing.T) {
-	input := `module calc
+	cases := []struct {
+		Name     string
+		Mod      string
+		Package  string
+		Expected string
+	}{
+		{
+			Name:     "simple require",
+			Mod:      "require    goa.design/goa/v3   v3.0.3-0.20190704022140-85024ebc66dc",
+			Package:  "goa.design/goa/v3",
+			Expected: "goa.design/goa/[email protected]",
+		},
+		{
+			Name: "in require block",
+			Mod: `module calc
 go 1.12
 require (
-        github.com/smartystreets/assertions v1.0.0 // indirect
+        github.com/ikawaha/kagome v1.0.0 // indirect
         goa.design/goa/v3 v3.0.3-0.20190704022140-85024ebc66dc
         goa.design/plugins/v3 v3.0.1
 )
-`
-	expected := `goa.design/goa/[email protected]`
-	pkg, err := parseGoModGoaPackage("goa.design/goa/v3", []byte(input))
-	if err != nil {
-		t.Fatalf("unexpected error, %v", err)
+`,
+			Package:  "goa.design/goa/v3",
+			Expected: `goa.design/goa/[email protected]`,
+		},
+		{
+			Name: "not found",
+			Mod: `module calc
+go 1.12
+require (
+        github.com/ikawaha/kagome v1.0.0 // indirect
+        goa.design/plugins/v3 v3.0.1
+)
+`,
+			Package:  "goa.design/goa/v3",
+			Expected: "goa.design/goa/v3",
+		},
+		{
+			Name: "with replace",
+			Mod: `module calc
+go 1.12
+replace goa.design/goa/v3 => ../../../goa.design/goa
+require (
+        github.com/ikawaha/kagome v1.0.0 // indirect
+        goa.design/goa/v3 v3.0.3-0.20190704022140-85024ebc66dc
+        goa.design/plugins/v3 v3.0.1
+)
+`,
+			Package:  "goa.design/goa/v3",
+			Expected: `goa.design/goa/[email protected]`,
+		},
 	}
-	if pkg != expected {
-		t.Errorf("expected %v, got %v", expected, pkg)
+	for _, c := range cases {
+		t.Run(c.Name, func(t *testing.T) {
+			pkg, err := parseGoModGoaPackage("goa.design/goa/v3", strings.NewReader(c.Mod))
+			if err != nil {
+				t.Fatalf("unexpected error, %v", err)
+			}
+			if pkg != c.Expected {
+				t.Errorf("expected %v, got %v", c.Expected, pkg)
+			}
+		})
 	}
 }