Merge pull request #635 from kayac/fix/diff-output-with-null

fix diff output compared with nil

diff.go

@@ -1,6 +1,7 @@
 package ecspresso
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
@@ -30,6 +31,7 @@ func (d *App) Diff(ctx context.Context, opt DiffOption) error {
 	var remoteTaskDefArn string
 	// diff for services only when service defined
 	if d.config.Service != "" {
+		d.Log("[DEGUG] diff service compare with %s", d.config.Service)
 		newSv, err := d.LoadServiceDefinition(d.config.ServiceDefinitionPath)
 		if err != nil {
 			return fmt.Errorf("failed to load service definition: %w", err)
@@ -70,6 +72,7 @@ func (d *App) Diff(ctx context.Context, opt DiffOption) error {
 	}
 	var remoteTd *ecs.RegisterTaskDefinitionInput
 	if remoteTaskDefArn != "" {
+		d.Log("[DEGUG] diff task definition compare with %s", remoteTaskDefArn)
 		remoteTd, err = d.DescribeTaskDefinition(ctx, remoteTaskDefArn)
 		if err != nil {
 			return err
@@ -112,8 +115,8 @@ func diffServices(local, remote *Service, localPath string, unified bool) (strin
 		return "", fmt.Errorf("failed to marshal remote service definition: %w", err)
 	}
 
-	remoteSv := string(remoteSvBytes)
-	newSv := string(newSvBytes)
+	remoteSv := toDiffString(remoteSvBytes)
+	newSv := toDiffString(newSvBytes)
 
 	if unified {
 		edits := myers.ComputeEdits(span.URIFromPath(remoteArn), remoteSv, newSv)
@@ -141,8 +144,8 @@ func diffTaskDefs(local, remote *TaskDefinitionInput, localPath, remoteArn strin
 		return "", fmt.Errorf("failed to marshal remote task definition: %w", err)
 	}
 
-	remoteTd := string(remoteTdBytes)
-	newTd := string(newTdBytes)
+	remoteTd := toDiffString(remoteTdBytes)
+	newTd := toDiffString(newTdBytes)
 
 	if unified {
 		edits := myers.ComputeEdits(span.URIFromPath(remoteArn), remoteTd, newTd)
@@ -341,3 +344,10 @@ func toNumberMemory(memory string) *string {
 	}
 	return &memory
 }
+
+func toDiffString(b []byte) string {
+	if bytes.Equal(b, []byte("null")) || bytes.Equal(b, []byte("null\n")) {
+		return ""
+	}
+	return string(b)
+}

diff_test.go

@@ -1,6 +1,7 @@
 package ecspresso_test
 
 import (
+	"strings"
 	"testing"
 
 	"github.com/aws/aws-sdk-go-v2/aws"
@@ -267,6 +268,15 @@ func TestDiffServices(t *testing.T) {
 		if diff == "" {
 			t.Errorf("unexpected diff: %s", diff)
 		}
+		minusDiffs := 0
+		for _, line := range strings.Split(diff, "\n") {
+			if strings.HasPrefix(line, "-") {
+				minusDiffs++
+			}
+		}
+		if minusDiffs != 1 {  // The first line is "---"
+			t.Errorf("unexpected diff. has many minus diffs: %s", diff)
+		}
 	})
 }
 
@@ -297,5 +307,14 @@ func TestDiffTaskDefs(t *testing.T) {
 		if diff == "" {
 			t.Errorf("unexpected diff: %s", diff)
 		}
+		minusDiffs := 0
+		for _, line := range strings.Split(diff, "\n") {
+			if strings.HasPrefix(line, "-") {
+				minusDiffs++
+			}
+		}
+		if minusDiffs != 1 { // The first line is "---"
+			t.Errorf("unexpected diff. has many minus diffs: %s", diff)
+		}
 	})
 }

json.go

@@ -12,7 +12,7 @@ import (
 func (d *App) OutputJSONForAPI(w io.Writer, v interface{}) error {
 	b, err := MarshalJSONForAPI(v)
 	if err != nil {
-		fmt.Errorf("failed to marshal json: %w", err)
+		return fmt.Errorf("failed to marshal json: %w", err)
 	}
 	_, err = w.Write(b)
 	return err