update cnf/common interface to implement io.ReaderFrom + io.WriterTo | tested ini+json file update

internal/cnf/common.go

@@ -6,11 +6,13 @@ import (
 
 // ConfigurationFormat is the common interface for all configuration parser
 type ConfigurationFormat interface {
-	// Read the given file
+	// ReadFrom the given file
-	Read(io.Reader) error
+	// implements io.ReaderFrom
+	ReadFrom(io.Reader) (int64, error)
 
-	// Write the given update to the file
+	// WriteTo a file the updated content
-	Write(io.Writer) error
+	// implements io.WriterTo
+	WriteTo(io.Writer) (int64, error)
 
 	// Get the value of a field if it exists
 	Get(string) (string, bool)

internal/cnf/ini.go

@@ -13,26 +13,25 @@ type Ini struct {
 	parsed   bool
 }
 
-// Read extract a reader as its JSON representation
+// ReadFrom implements io.ReaderFrom
-func (d *Ini) Read(_reader io.Reader) error {
+func (d *Ini) ReadFrom(_reader io.Reader) (int64, error) {
 
 	// 1. get json decoder
 	file, err := ini.Load(ioutil.NopCloser(_reader))
 	if err != nil {
-		return err
+		return 0, err
 	}
 
 	d.data = file
 	d.sections = file.SectionStrings()
 	d.parsed = true
-	return nil
+	return 0, nil
 
 }
 
-// Write the INI representation to a writer
+// WriteTo implements io.WriterTo
-func (d *Ini) Write(_writer io.Writer) error {
+func (d *Ini) WriteTo(_writer io.Writer) (int64, error) {
-	_, err := d.data.WriteTo(_writer)
+	return d.data.WriteTo(_writer)
-	return err
 }
 
 // Get returns the value of a dot-separated path, and if it exists

internal/cnf/ini_test.go

@@ -22,7 +22,7 @@ func TestIniGet(t *testing.T) {
 		reader := bytes.NewBufferString(test.raw)
 
 		// try to extract value
-		err := parser.Read(reader)
+		_, err := parser.ReadFrom(reader)
 		if err != nil {
 			t.Errorf("parse error: %s", err)
 			continue
@@ -62,7 +62,7 @@ func TestIniSetPathExists(t *testing.T) {
 		reader := bytes.NewBufferString(test.raw)
 
 		// try to extract value
-		err := parser.Read(reader)
+		_, err := parser.ReadFrom(reader)
 		if err != nil {
 			t.Errorf("parse error: %s", err)
 			continue
@@ -110,7 +110,7 @@ func TestIniSetCreatePath(t *testing.T) {
 		reader := bytes.NewBufferString(test.raw)
 
 		// try to extract value
-		err := parser.Read(reader)
+		_, err := parser.ReadFrom(reader)
 		if err != nil {
 			t.Errorf("[%d] parse error: %s", i, err)
 			continue

internal/cnf/json.go

@@ -11,25 +11,26 @@ type Json struct {
 	parsed bool
 }
 
-// Read extract a reader as its JSON representation
+// ReadFrom implements io.ReaderFrom
-func (d *Json) Read(_reader io.Reader) error {
+func (d *Json) ReadFrom(_reader io.Reader) (int64, error) {
 
 	// 1. get json decoder
 	decoder := json.NewDecoder(_reader)
 	err := decoder.Decode(&d.data)
 	if err != nil {
-		return err
+		return 0, err
 	}
 
 	d.parsed = true
-	return nil
+	return 0, nil
 
 }
 
-// Write the JSON representation to a writer
+// WriteTo implements io.WriterTo
-func (d *Json) Write(_writer io.Writer) error {
+func (d *Json) WriteTo(_writer io.Writer) (int64, error) {
 	encoder := json.NewEncoder(_writer)
-	return encoder.Encode(&d.data)
+	encoder.SetIndent("", "\t")
+	return 0, encoder.Encode(&d.data)
 }
 
 // browse returns the target of a dot-separated path (as an interface{} chain where the last is the target if found)

internal/cnf/json_test.go

@@ -23,7 +23,7 @@ func TestJsonGet(t *testing.T) {
 		reader := bytes.NewBufferString(test.raw)
 
 		// try to extract value
-		err := parser.Read(reader)
+		_, err := parser.ReadFrom(reader)
 		if err != nil {
 			t.Errorf("parse error: %s", err)
 			continue
@@ -63,7 +63,7 @@ func TestJsonGetNotString(t *testing.T) {
 		reader := bytes.NewBufferString(test.raw)
 
 		// try to extract value
-		err := parser.Read(reader)
+		_, err := parser.ReadFrom(reader)
 		if err != nil {
 			t.Errorf("parse error: %s", err)
 			continue
@@ -99,7 +99,7 @@ func TestJsonSetPathExistsAndIsString(t *testing.T) {
 		reader := bytes.NewBufferString(test.raw)
 
 		// try to extract value
-		err := parser.Read(reader)
+		_, err := parser.ReadFrom(reader)
 		if err != nil {
 			t.Errorf("parse error: %s", err)
 			continue
@@ -150,7 +150,7 @@ func TestJsonSetCreatePath(t *testing.T) {
 		reader := bytes.NewBufferString(test.raw)
 
 		// try to extract value
-		err := parser.Read(reader)
+		_, err := parser.ReadFrom(reader)
 		if err != nil {
 			t.Errorf("[%d] parse error: %s", i, err)
 			continue

internal/cnf/loader.go

@@ -38,7 +38,7 @@ func Load(path string) (ConfigurationFormat, error) {
 		defer file.Close()
 
 		// parse
-		err = confFormat.Read(file)
+		_, err = confFormat.ReadFrom(file)
 		if err != nil {
 			return nil, fmt.Errorf("cannot parse file as '%s' | %s", extension, err)
 		}

internal/instruction/cnf.go

@@ -72,7 +72,7 @@ func (d config) Exec(ctx ExecutionContext) ([]byte, error) {
 		return nil, err
 	}
 	defer file.Close()
-	if err = format.Write(file); err != nil {
+	if _, err = format.WriteTo(file); err != nil {
 		return nil, err
 	}