Use "." to refer to the current path's package in reflect mode (#387)

* feat: use "." to refer to the current path's package

* doc: update reflect mode

* fix: generated code lose package name

Author: XSAM

Diff for: README.md

@@ -51,10 +51,15 @@ that uses reflection to understand interfaces. It is enabled
 by passing two non-flag arguments: an import path, and a
 comma-separated list of symbols.
 
+You can use "." to refer to the current path's package.
+
 Example:
 
 ```bash
 mockgen database/sql/driver Conn,Driver
+
+# Convenient for `go:generate`.
+mockgen . Conn,Driver
 ```
 
 The `mockgen` command is used to generate source code for a mock

Diff for: mockgen/mockgen.go

@@ -69,14 +69,26 @@ func main() {
 
 	var pkg *model.Package
 	var err error
+	var packageName string
 	if *source != "" {
 		pkg, err = sourceMode(*source)
 	} else {
 		if flag.NArg() != 2 {
 			usage()
 			log.Fatal("Expected exactly two arguments")
 		}
-		pkg, err = reflectMode(flag.Arg(0), strings.Split(flag.Arg(1), ","))
+		packageName = flag.Arg(0)
+		if packageName == "." {
+			dir, err := os.Getwd()
+			if err != nil {
+				log.Fatalf("Get current directory failed: %v", err)
+			}
+			packageName, err = packageNameOfDir(dir)
+			if err != nil {
+				log.Fatalf("Parse package name failed: %v", err)
+			}
+		}
+		pkg, err = reflectMode(packageName, strings.Split(flag.Arg(1), ","))
 	}
 	if err != nil {
 		log.Fatalf("Loading input failed: %v", err)
@@ -130,7 +142,7 @@ func main() {
 	if *source != "" {
 		g.filename = *source
 	} else {
-		g.srcPackage = flag.Arg(0)
+		g.srcPackage = packageName
 		g.srcInterfaces = flag.Arg(1)
 	}
 

Diff for: mockgen/parse.go

@@ -24,6 +24,7 @@ import (
 	"go/build"
 	"go/parser"
 	"go/token"
+	"io/ioutil"
 	"log"
 	"path"
 	"path/filepath"
@@ -48,19 +49,10 @@ func sourceMode(source string) (*model.Package, error) {
 		return nil, fmt.Errorf("failed getting source directory: %v", err)
 	}
 
-	cfg := &packages.Config{Mode: packages.LoadFiles, Tests: true, Dir: srcDir}
-	pkgs, err := packages.Load(cfg, "file="+source)
+	packageImport, err := parsePackageImport(source, srcDir)
 	if err != nil {
 		return nil, err
 	}
-	if packages.PrintErrors(pkgs) > 0 || len(pkgs) == 0 {
-		return nil, errors.New("loading package failed")
-	}
-
-	packageImport := pkgs[0].PkgPath
-
-	// It is illegal to import a _test package.
-	packageImport = strings.TrimSuffix(packageImport, "_test")
 
 	fs := token.NewFileSet()
 	file, err := parser.ParseFile(fs, source, nil, 0)
@@ -519,3 +511,46 @@ func isVariadic(f *ast.FuncType) bool {
 	_, ok := f.Params.List[nargs-1].Type.(*ast.Ellipsis)
 	return ok
 }
+
+// packageNameOfDir get package import path via dir
+func packageNameOfDir(srcDir string) (string, error) {
+	files, err := ioutil.ReadDir(srcDir)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	var goFilePath string
+	for _, file := range files {
+		if !file.IsDir() && strings.HasSuffix(file.Name(), ".go") {
+			goFilePath = file.Name()
+			break
+		}
+	}
+	if goFilePath == "" {
+		return "", fmt.Errorf("go source file not found %s", srcDir)
+	}
+
+	packageImport, err := parsePackageImport(goFilePath, srcDir)
+	if err != nil {
+		return "", err
+	}
+	return packageImport, nil
+}
+
+// parseImportPackage get package import path via source file
+func parsePackageImport(source, srcDir string) (string, error) {
+	cfg := &packages.Config{Mode: packages.LoadFiles, Tests: true, Dir: srcDir}
+	pkgs, err := packages.Load(cfg, "file="+source)
+	if err != nil {
+		return "", err
+	}
+	if packages.PrintErrors(pkgs) > 0 || len(pkgs) == 0 {
+		return "", errors.New("loading package failed")
+	}
+
+	packageImport := pkgs[0].PkgPath
+
+	// It is illegal to import a _test package.
+	packageImport = strings.TrimSuffix(packageImport, "_test")
+	return packageImport, nil
+}