Merge pull request #59 from LandonTClipp/copy

Add wrapper around `io.Copy`

Author: LandonTClipp

path.go

@@ -615,6 +615,24 @@ func (p *Path) Mtime() (time.Time, error) {
 	return Mtime(stat)
 }
 
+// Copy copies the path to another path using io.Copy.
+// Returned is the number of bytes copied and any error values.
+// The destination file is truncated if it exists, and is created
+// if it does not exist.
+func (p *Path) Copy(other *Path) (int64, error) {
+	srcFile, err := p.Open()
+	if err != nil {
+		return 0, fmt.Errorf("opening source file: %w", err)
+	}
+	defer srcFile.Close()
+	dstFile, err := other.OpenFile(os.O_TRUNC | os.O_CREATE | os.O_WRONLY)
+	if err != nil {
+		return 0, fmt.Errorf("opening destination file: %w", err)
+	}
+	defer dstFile.Close()
+	return io.Copy(dstFile, srcFile)
+}
+
 // Mtime returns the mtime described in the given os.FileInfo object
 func Mtime(fileInfo os.FileInfo) (time.Time, error) {
 	return fileInfo.ModTime(), nil

path_test.go

@@ -502,3 +502,76 @@ func TestPath_Parts(t *testing.T) {
 		})
 	}
 }
+
+func TestPath_Copy(t *testing.T) {
+	tests := []struct {
+		name            string
+		srcContents     string
+		dstContents     string
+		wantDstContents string
+		createDstFile   bool
+		wantErr         bool
+	}{
+		{
+			name:            "copy empty file to existing non-empty file",
+			srcContents:     "",
+			dstContents:     "foobar",
+			wantDstContents: "",
+			createDstFile:   true,
+		},
+		{
+			name:            "copy empty file to existing empty file",
+			srcContents:     "",
+			dstContents:     "",
+			wantDstContents: "",
+			createDstFile:   true,
+		},
+		{
+			name:            "copy empty file to non-existing file",
+			srcContents:     "",
+			wantDstContents: "",
+			createDstFile:   false,
+		},
+		{
+			name:            "copy non-empty file to existing non-empty file",
+			srcContents:     "foobar",
+			dstContents:     "hello world",
+			wantDstContents: "foobar",
+			createDstFile:   true,
+		},
+		{
+			name:            "copy non-empty file to existing empty file",
+			srcContents:     "foobar",
+			dstContents:     "",
+			wantDstContents: "foobar",
+			createDstFile:   true,
+		},
+		{
+			name:            "copy non-empty file to non-existing file",
+			srcContents:     "foobar",
+			wantDstContents: "foobar",
+			createDstFile:   false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			tmpdir := NewPath(t.TempDir())
+			src := tmpdir.Join("src.txt")
+			dst := tmpdir.Join("dst.txt")
+			require.NoError(t, src.WriteFile([]byte(tt.srcContents)))
+
+			if tt.createDstFile {
+				require.NoError(t, dst.WriteFile([]byte(tt.dstContents)))
+			}
+
+			_, err := src.Copy(dst)
+			if !tt.wantErr {
+				require.NoError(t, err)
+			}
+
+			dstBytes, err := dst.ReadFile()
+			require.NoError(t, err)
+			assert.Equal(t, []byte(tt.wantDstContents), dstBytes)
+		})
+	}
+}