refactor: restructure code to enhance testability

cmd/mkf/main.go

@@ -2,29 +2,37 @@ package main
 
 import (
 	"fmt"
+	"io/fs"
 	"os"
 
-	"github.com/gm0stache/utils/internal/pathspltr"
+	"github.com/gm0stache/utils/internal/fspath"
 )
 
 const (
 	default_dir_permissons_code = 0700
 )
 
+type RealFsCreator struct {
+}
+
+func (rc *RealFsCreator) MkdirAll(path string, perm fs.FileMode) error {
+	return os.MkdirAll(path, perm)
+}
+
+func (rc *RealFsCreator) Create(name string) error {
+	_, err := os.Create(name)
+	return err
+}
+
 func main() {
 	args := os.Args
 	if len(args) != 2 {
-		fmt.Println("invalid invocation. Usage: mkf file_path")
+		fmt.Println("invalid invocation.\nusage: mkf file_path")
 		os.Exit(-1)
 	}
+	creator := RealFsCreator{}
 	filePath := args[1]
-	pathComponents := pathspltr.GetFilePathParts(filePath)
-	err := os.MkdirAll(pathComponents.DirPath, default_dir_permissons_code)
-	if err != nil {
-		fmt.Printf("Error:\n%s", err.Error())
-		os.Exit(-1)
-	}
-	_, err = os.Create(filePath)
+	err := fspath.CreateFile(&creator, filePath)
 	if err != nil {
 		fmt.Printf("Error:\n%s", err.Error())
 		os.Exit(-1)

go.mod

@@ -7,5 +7,7 @@ require github.com/stretchr/testify v1.8.4
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/spf13/afero v1.11.0 // indirect
+	golang.org/x/text v0.14.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -2,8 +2,12 @@ github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/spf13/afero v1.11.0 h1:WJQKhtpdm3v2IzqG8VMqrr6Rf3UYpEF239Jy9wNepM8=
+github.com/spf13/afero v1.11.0/go.mod h1:GH9Y3pIexgf1MTIWtNGyogA5MwRIDXGUr+hbWNoBjkY=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
+golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

internal/fspath/filecreator.go

@@ -0,0 +1,25 @@
+package fspath
+
+import (
+	"io/fs"
+)
+
+const (
+	default_dir_permissons_code = 0700
+)
+
+type FsCreator interface {
+	MkdirAll(path string, perm fs.FileMode) error
+	Create(name string) error
+}
+
+// CreateFile creates all missing parent dir's in the file and the file itself.
+func CreateFile(creator FsCreator, path string) error {
+	pathComponents := getPathComponents(path)
+	err := creator.MkdirAll(pathComponents.DirPath, default_dir_permissons_code)
+	if err != nil {
+		return err
+	}
+	err = creator.Create(path)
+	return err
+}

internal/fspath/filecreator_test.go

@@ -0,0 +1,47 @@
+package fspath
+
+import (
+	"io/fs"
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/assert"
+)
+
+type fakeFsCreator struct {
+	fs *afero.MemMapFs
+}
+
+func (rc *fakeFsCreator) MkdirAll(path string, perm fs.FileMode) error {
+	return rc.fs.MkdirAll(path, perm)
+}
+
+func (rc *fakeFsCreator) Create(name string) error {
+	_, err := rc.fs.Create(name)
+	return err
+}
+
+func TestFsCreator(t *testing.T) {
+	cases := map[string]string{
+		"simple file":                   "./exampleDir/example.txt",
+		"dotfile, relative to user dir": "~/.config/.vimrc",
+		"multi-dot-file, deeply nested": "./test/test/test/testing.dev.env",
+	}
+
+	// arrange
+	fakeFS := fakeFsCreator{
+		fs: new(afero.MemMapFs),
+	}
+
+	for name, path := range cases {
+		t.Run(name, func(t *testing.T) {
+			// act
+			err := CreateFile(&fakeFS, path)
+
+			// assert
+			assert.NoError(t, err)
+			// fileExists, _ := fakeFS.fs.Exists(path)
+			// assert.True(t, fileExists, "file should be created")
+		})
+	}
+}

internal/pathspltr/pathspltr.go → internal/fspath/pathspltr.go

@@ -1,16 +1,16 @@
-package pathspltr
+package fspath
 
 import (
 	"path/filepath"
 )
 
-type PathComponent struct {
+type pathComponents struct {
 	Filename string
 	DirPath  string
 }
 
-func GetFilePathParts(path string) PathComponent {
-	return PathComponent{
+func getPathComponents(path string) pathComponents {
+	return pathComponents{
 		Filename: filepath.Base(path),
 		DirPath:  filepath.Dir(path),
 	}

internal/pathspltr/pathspltr_test.go → internal/fspath/pathspltr_test.go

@@ -1,4 +1,4 @@
-package pathspltr
+package fspath
 
 import (
 	"testing"
@@ -37,7 +37,7 @@ func TestFilePathSplitting(t *testing.T) {
 	for testname, testData := range cases {
 		t.Run(testname, func(t *testing.T) {
 			// act
-			pathComponents := GetFilePathParts(testData.givenPath)
+			pathComponents := getPathComponents(testData.givenPath)
 
 			// assert
 			assert.EqualValues(t, pathComponents.DirPath, testData.expectedDirPath)