add interfaces flag with unit test

mockgen/parse.go

@@ -18,6 +18,7 @@ package main
 
 import (
 	"errors"
+	"flag"
 	"fmt"
 	"go/ast"
 	"go/build"
@@ -29,6 +30,7 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"sort"
 	"strconv"
 	"strings"
 
@@ -61,6 +63,20 @@ func sourceMode(source string) (*model.Package, error) {
 		srcDir:             srcDir,
 	}
 
+	// positional interface names -> include set
+	ifaces := flag.Args()
+	if len(ifaces) > 0 {
+		p.includeNamesSet = make(map[string]struct{}, len(ifaces))
+		for _, arg := range ifaces {
+			for _, name := range strings.Split(arg, ",") {
+				name = strings.TrimSpace(name)
+				if name != "" {
+					p.includeNamesSet[name] = struct{}{}
+				}
+			}
+		}
+	}
+
 	// Handle -imports.
 	dotImports := make(map[string]bool)
 	if *imports != "" {
@@ -92,6 +108,7 @@ func sourceMode(source string) (*model.Package, error) {
 	for pkgPath := range dotImports {
 		pkg.DotImports = append(pkg.DotImports, pkgPath)
 	}
+
 	return pkg, nil
 }
 
@@ -168,6 +185,7 @@ type fileParser struct {
 	auxInterfaces      *interfaceCache
 	srcDir             string
 	excludeNamesSet    map[string]struct{}
+	includeNamesSet    map[string]struct{}
 }
 
 func (p *fileParser) errorf(pos token.Pos, format string, args ...any) error {
@@ -228,17 +246,36 @@ func (p *fileParser) parseFile(importPath string, file *ast.File) (*model.Packag
 
 	var is []*model.Interface
 	for ni := range iterInterfaces(file) {
-		if _, ok := p.excludeNamesSet[ni.name.String()]; ok {
+		name := ni.name.String()
+
+		if _, ok := p.excludeNamesSet[name]; ok {
 			continue
 		}
-		i, err := p.parseInterface(ni.name.String(), importPath, ni)
+
+		if len(p.includeNamesSet) > 0 {
+			if _, ok := p.includeNamesSet[name]; !ok {
+				continue
+			}
+		}
+
+		i, err := p.parseInterface(name, importPath, ni)
 		if errors.Is(err, errConstraintInterface) {
 			continue
 		}
 		if err != nil {
 			return nil, err
 		}
 		is = append(is, i)
+
+		delete(p.includeNamesSet, name)
+	}
+	if len(p.includeNamesSet) > 0 {
+		missing := make([]string, 0, len(p.includeNamesSet))
+		for n := range p.includeNamesSet {
+			missing = append(missing, n)
+		}
+		sort.Strings(missing)
+		return nil, fmt.Errorf("requested interfaces not found: %s", strings.Join(missing, ", "))
 	}
 	return &model.Package{
 		Name:       file.Name.String(),

mockgen/parse_test.go

@@ -3,6 +3,7 @@ package main
 import (
 	"go/parser"
 	"go/token"
+	"strings"
 	"testing"
 )
 
@@ -143,3 +144,84 @@ func TestParseArrayWithConstLength(t *testing.T) {
 		}
 	}
 }
+
+func TestParseFile_IncludeOnlyRequested(t *testing.T) {
+	fs := token.NewFileSet()
+	file, err := parser.ParseFile(fs, "internal/tests/custom_package_name/greeter/greeter.go", nil, 0)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	p := fileParser{
+		fileSet:            fs,
+		imports:            make(map[string]importedPackage),
+		importedInterfaces: newInterfaceCache(),
+		// include только один интерфейс
+		includeNamesSet: map[string]struct{}{"InputMaker": {}},
+	}
+
+	pkg, err := p.parseFile("", file)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	if len(pkg.Interfaces) != 1 || pkg.Interfaces[0].Name != "InputMaker" {
+		t.Fatalf("Expected only InputMaker, got %v", pkg.Interfaces)
+	}
+}
+
+func TestParseFile_IncludeMissing_ReturnsError(t *testing.T) {
+	fs := token.NewFileSet()
+	file, err := parser.ParseFile(fs, "internal/tests/custom_package_name/greeter/greeter.go", nil, 0)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	p := fileParser{
+		fileSet:            fs,
+		imports:            make(map[string]importedPackage),
+		importedInterfaces: newInterfaceCache(),
+		includeNamesSet:    map[string]struct{}{"DoesNotExist": {}},
+	}
+
+	_, err = p.parseFile("", file)
+	if err == nil || !strings.Contains(err.Error(), "requested interfaces not found") {
+		t.Fatalf("Expected missing interface error, got %v", err)
+	}
+}
+
+func TestParseFile_IncludeWithDuplicates_Dedupes(t *testing.T) {
+	fs := token.NewFileSet()
+	file, err := parser.ParseFile(fs, "internal/tests/custom_package_name/greeter/greeter.go", nil, 0)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	// Эмулируем «случайно указали дубликаты» как это делает sourceMode (через позиционные аргументы)
+	args := []string{"InputMaker", "InputMaker"} // дубликаты
+	include := make(map[string]struct{})
+	for _, a := range args {
+		for _, name := range strings.Split(a, ",") {
+			name = strings.TrimSpace(name)
+			if name != "" {
+				include[name] = struct{}{}
+			}
+		}
+	}
+
+	p := fileParser{
+		fileSet:            fs,
+		imports:            make(map[string]importedPackage),
+		importedInterfaces: newInterfaceCache(),
+		includeNamesSet:    include,
+	}
+
+	pkg, err := p.parseFile("", file)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	if len(pkg.Interfaces) != 1 || pkg.Interfaces[0].Name != "InputMaker" {
+		t.Fatalf("Expected only InputMaker once, got %v", pkg.Interfaces)
+	}
+}