V3: Fix to use the version of goa specified in go.mod file, when 'goa gen'/'goa example'

cmd/goa/gen.go

@@ -1,9 +1,11 @@
 package main
 
 import (
+	"bufio"
 	"fmt"
 	"go/parser"
 	"go/token"
+	"io"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -141,11 +143,59 @@ func (g *Generator) Write(debug bool) error {
 	return err
 }
 
+const goModEnvKey = "GOMOD"
+
+func findGoMod() string {
+	env := os.Getenv(goModEnvKey)
+	if _, err := exec.LookPath("go"); err != nil {
+		return env
+	}
+	mod, err := exec.Command("go", "env", goModEnvKey).Output()
+	if err != nil {
+		return env
+	}
+	return strings.TrimSpace(string(mod))
+}
+
+func (g *Generator) goaPackage() (string, error) {
+	goaPkg := "goa.design/goa"
+	if g.DesignVersion < 3 {
+		return goaPkg, nil
+	}
+	goaPkg = fmt.Sprintf("goa.design/goa/v%d", g.DesignVersion)
+	path := findGoMod()
+	if _, err := os.Stat(path); err != nil {
+		return goaPkg, nil
+	}
+	fp, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer fp.Close()
+	return parseGoModGoaPackage(goaPkg, fp)
+}
+
+var reMod = regexp.MustCompile(`^\s*(?:require )?\s*(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 err := s.Err(); err != nil {
+		return "", fmt.Errorf("scan error, %v", err)
+	}
+	return pkg, nil
+}
+
 // Compile compiles the generator.
 func (g *Generator) Compile() error {
-	goaPkg := "goa.design/goa"
-	if g.DesignVersion > 2 {
-		goaPkg = fmt.Sprintf("goa.design/goa/v%d", g.DesignVersion)
+	goaPkg, err := g.goaPackage()
+	if err != nil {
+		return err
 	}
 	if err := g.runGoCmd("get", goaPkg); err != nil {
 		return err

cmd/goa/gen_test.go

@@ -0,0 +1,210 @@
+package main
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestGenerator_goaPackage(t *testing.T) {
+	cases := []struct {
+		Name     string
+		Version  int
+		Expected string
+	}{
+		{
+			Name:     "specify v2",
+			Version:  2,
+			Expected: "goa.design/goa",
+		},
+		{
+			Name:     "specify v3, but go.mod file does not exist",
+			Version:  3,
+			Expected: "goa.design/goa/v3",
+		},
+	}
+	for _, c := range cases {
+		t.Run(c.Name, func(t *testing.T) {
+			pkg, err := (&Generator{
+				DesignVersion: c.Version,
+			}).goaPackage()
+			if err != nil {
+				t.Fatalf("unexpected error, %v", err)
+			}
+			if pkg != c.Expected {
+				t.Errorf("expected %v, got %v", c.Expected, pkg)
+			}
+		})
+	}
+}
+
+func TestParseGoModGoaPackage(t *testing.T) {
+	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/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]",
+		},
+		{
+			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]",
+		},
+		{
+			Name: "with comment",
+			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 // indirect // comment
+        goa.design/plugins/v3 v3.0.1
+)
+`,
+			Package:  "goa.design/goa/v3",
+			Expected: "goa.design/goa/[email protected]",
+		},
+		{
+			Name:     "require with comment",
+			Mod:      " require goa.design/goa/v3 v3.0.3-0.20190704022140-85024ebc66dc// indirect // comment",
+			Package:  "goa.design/goa/v3",
+			Expected: "goa.design/goa/[email protected]",
+		},
+		{
+			Name: "comment out",
+			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/v3",
+		},
+		{
+			Name:     "without version",
+			Mod:      "     goa.design/goa/v3//v3.0.3-0.20190704022140-85024ebc66dc",
+			Package:  "goa.design/goa/v3",
+			Expected: "goa.design/goa/v3",
+		},
+		{
+			Name:     "different version",
+			Mod:      "goa.design/goa/v2 v2.0.3-0.20190704022140-85024ebc66dc // comment",
+			Package:  "goa.design/goa/v3",
+			Expected: "goa.design/goa/v3",
+		},
+	}
+	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)
+			}
+		})
+	}
+}
+
+func TestModPatternRegexp(t *testing.T) {
+	cases := []struct {
+		Name     string
+		Input    string
+		Expected []string
+	}{
+		{
+			Name:     "goa v3 release version",
+			Input:    "goa.design/goa/v3 v3.0.2",
+			Expected: []string{"goa.design/goa/v3 v3.0.2", "goa.design/goa/v3", "v3.0.2"},
+		},
+		{
+			Name:     "goa v3 commit number",
+			Input:    "goa.design/goa/v3 02c84c9b39d845611bfe6e8a96465d698ea374b1",
+			Expected: []string{"goa.design/goa/v3 02c84c9b39d845611bfe6e8a96465d698ea374b1", "goa.design/goa/v3", "02c84c9b39d845611bfe6e8a96465d698ea374b1"},
+		},
+		{
+			Name:     "goa v3 with comment",
+			Input:    "goa.design/goa/v3   v3.0.2 //comment1 //comment2 //comment3",
+			Expected: []string{"goa.design/goa/v3   v3.0.2 //comment1 //comment2 //comment3", "goa.design/goa/v3", "v3.0.2"},
+		},
+		{
+			Name:     "goa v3 with require and comment",
+			Input:    "require goa.design/goa/v3 v3.0.2 //comment",
+			Expected: []string{"require goa.design/goa/v3 v3.0.2 //comment", "goa.design/goa/v3", "v3.0.2"},
+		},
+		{
+			Name:     "goa v2",
+			Input:    "goa.design/goa/v2 v2.0.0",
+			Expected: []string{"goa.design/goa/v2 v2.0.0", "goa.design/goa/v2", "v2.0.0"},
+		},
+		{
+			Name:     "goa v123",
+			Input:    "   goa.design/goa/v123    v123.4.5   ",
+			Expected: []string{"   goa.design/goa/v123    v123.4.5   ", "goa.design/goa/v123", "v123.4.5"},
+		},
+		{
+			Name:     "without version",
+			Input:    "goa.design/goa/v3",
+			Expected: nil,
+		},
+		{
+			Name:     "comment out",
+			Input:    "// goa.design/goa/v3 v3.0.0",
+			Expected: nil,
+		},
+		{
+			Name:     "irrelevant package",
+			Input:    "github.com/ikawaha/kagome v1.10.0",
+			Expected: nil,
+		},
+	}
+	for _, c := range cases {
+		if got := reMod.FindStringSubmatch(c.Input); !reflect.DeepEqual(c.Expected, got) {
+			t.Errorf("expected %+v, got %+v", c.Expected, got)
+		}
+	}
+}