Add Copy() method

Author: leaanthony

README.md

@@ -3,7 +3,7 @@
 </p>
 
 <p align="center">
-	Yo dawg! I heard you liked <code>embed.FS</code>...<br/><br/>
+   <code>embed.FS</code> wrapper providing additional functionality<br/><br/>
    <a href="https://github.com/leaanthony/debme/blob/master/LICENSE"><img src="https://img.shields.io/badge/License-MIT-blue.svg"></a>
    <a href="https://goreportcard.com/report/github.com/leaanthony/debme"><img src="https://goreportcard.com/badge/github.com/leaanthony/debme"/></a>
    <a href="https://godoc.org/github.com/leaanthony/debme"><img src="https://img.shields.io/badge/godoc-reference-blue.svg"/></a>
@@ -15,9 +15,8 @@
 
 ## Features
 
-  * Provides a way to get an `embed.FS` from an embedded directory
-  * One method: `FS()`
-  * You can keep calling `FS()`, all the way down...
+  * Get an `embed.FS` from an embedded subdirectory
+  * Handy `Copy(sourcePath, targetPath)` method to copy an embedded file to the filesystem
   * 100% `embed.FS` compatible
   * 100% code coverage
 
@@ -86,6 +85,9 @@ func main() {
 
 	println(len(deeperFiles)) // 1
 	println(files1[0].Name()) // "three.txt"
+	
+	// Copy files
+	err := deeper.Copy("three.txt", "/path/to/target.txt")
 }
 ```
 

debme.go

@@ -2,7 +2,9 @@ package debme
 
 import (
 	"embed"
+	"io"
 	"io/fs"
+	"os"
 	"path/filepath"
 )
 
@@ -52,3 +54,16 @@ func (d Debme) FS(subDir string) (Debme, error) {
 	path := d.calculatePath(subDir)
 	return FS(d.embedFS, path)
 }
+
+func (d Debme) CopyFile(sourcePath string, target string, perm os.FileMode) error {
+	sourceFile, err := d.Open(sourcePath)
+	if err != nil {
+		return err
+	}
+	targetFile, err := os.OpenFile(target, os.O_CREATE, perm)
+	if err != nil {
+		return err
+	}
+	_, err = io.Copy(targetFile, sourceFile)
+	return err
+}

debme_test.go

@@ -6,6 +6,7 @@ import (
 	"github.com/matryer/is"
 	"io"
 	"io/fs"
+	"os"
 	"testing"
 )
 
@@ -93,3 +94,25 @@ func TestFS(t *testing.T) {
 	_, err := FS(testfixtures, "baddir")
 	is2.True(err != nil)
 }
+
+func TestCopy(t *testing.T) {
+	is2 := is.New(t)
+	inner, err := FS(testfixtures, "fixtures/test2/inner")
+	is2.NoErr(err)
+	err = inner.CopyFile("one.txt", "one.txt", 0644)
+	is2.NoErr(err)
+	sourceData, err := inner.ReadFile("one.txt")
+	is2.NoErr(err)
+	targetData, err := os.ReadFile("one.txt")
+	is2.NoErr(err)
+	is2.Equal(sourceData, targetData)
+
+	// Bad source file
+	err = inner.CopyFile("one.txtsd", "one.txt", 0644)
+	is2.True(err != nil)
+
+	// Bad target file
+	err = inner.CopyFile("one.txt", "/:09/one.txt", 0644)
+	is2.True(err != nil)
+
+}