extract writeLimits from apiconfig.runNew and add tests

cmd/slackdump/internal/apiconfig/apiconfig.go

@@ -32,28 +32,48 @@ configuration file.
 var ErrConfigInvalid = errors.New("config validation failed")
 
 // Load reads, parses and validates the config file.
-func Load(filename string) (*slackdump.Limits, error) {
+func Load(filename string) (slackdump.Limits, error) {
 	f, err := os.Open(filename)
 	if err != nil {
-		return nil, err
+		return slackdump.Limits{}, err
 	}
 	defer f.Close()
 
+	return readLimits(f)
+}
+
+func Save(filename string, limits *slackdump.Limits) error {
+	f, err := os.Create(filename)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	return writeLimits(f, limits)
+}
+
+func readLimits(r io.Reader) (slackdump.Limits, error) {
 	var limits slackdump.Limits
-	dec := yaml.NewDecoder(f, yaml.DisallowUnknownField(), yaml.DisallowDuplicateKey())
+	dec := yaml.NewDecoder(r, yaml.DisallowUnknownField(), yaml.DisallowDuplicateKey())
 	if err := dec.Decode(&limits); err != nil {
-		return nil, err
+		return slackdump.Limits{}, err
 	}
 
 	if err := cfg.SlackOptions.Limits.Apply(limits); err != nil {
 		if err := printErrors(os.Stderr, err); err != nil {
-			return nil, err
+			return slackdump.Limits{}, err
 		}
-		return nil, ErrConfigInvalid
+		return slackdump.Limits{}, ErrConfigInvalid
 	}
-	return &limits, nil
+	return limits, nil
+}
+
+func writeLimits(w io.Writer, cfg *slackdump.Limits) error {
+	return yaml.NewEncoder(w).Encode(&slackdump.DefOptions.Limits)
 }
 
+// printErrors prints configuration errors, if error is not nill and is of
+// validator.ValidationErrors type.
 func printErrors(w io.Writer, err error) error {
 	if err == nil {
 		return nil

cmd/slackdump/internal/apiconfig/apiconfig_test.go

@@ -0,0 +1,71 @@
+package apiconfig
+
+import (
+	"io"
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/rusq/slackdump/v2"
+)
+
+const sampleLimitsYaml = `workers: 4
+download_retries: 3
+tier_2:
+  boost: 20
+  burst: 1
+  retries: 20
+tier_3:
+  boost: 120
+  burst: 1
+  retries: 3
+per_request:
+  conversations: 100
+  channels: 100
+  replies: 200
+`
+
+func Test_readConfig(t *testing.T) {
+	type args struct {
+		r io.Reader
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    slackdump.Limits
+		wantErr bool
+	}{
+		{
+			"sample config (ok)",
+			args{strings.NewReader(sampleLimitsYaml)},
+			slackdump.DefOptions.Limits,
+			false,
+		},
+		{
+			"workers invalid",
+			args{strings.NewReader("workers: -1")},
+			slackdump.Limits{},
+			true,
+		},
+		{
+			"one parameter override",
+			args{strings.NewReader("workers: 55")},
+			slackdump.Limits{
+				Workers: 55,
+			},
+			false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := readLimits(tt.args.r)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("readConfig() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("readConfig() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

cmd/slackdump/internal/apiconfig/new.go

@@ -7,8 +7,6 @@ import (
 	"os"
 	"path/filepath"
 
-	"github.com/goccy/go-yaml"
-
 	"github.com/rusq/slackdump/v2"
 	"github.com/rusq/slackdump/v2/cmd/slackdump/internal/cfg"
 	"github.com/rusq/slackdump/v2/cmd/slackdump/internal/golang/base"
@@ -55,13 +53,7 @@ func runConfigNew(ctx context.Context, cmd *base.Command, args []string) error {
 		return fmt.Errorf("refusing to overwrite file %q, use -y flag to overwrite", filename)
 	}
 
-	f, err := os.Create(filename)
-	if err != nil {
-		return fmt.Errorf("unable to create a new API config file: %w", err)
-	}
-	defer f.Close()
-
-	if err := yaml.NewEncoder(f).Encode(&slackdump.DefOptions); err != nil {
+	if err := Save(filename, &slackdump.DefOptions.Limits); err != nil {
 		base.SetExitStatus(base.SApplicationError)
 		return fmt.Errorf("error writing the API config %q: %w", filename, err)
 	}

cmd/slackdump/main.go

@@ -172,7 +172,7 @@ func parseFlags(cmd *base.Command, args []string) ([]string, error) {
 	if err != nil {
 		return nil, err
 	}
-	if err := cfg.SlackOptions.Limits.Apply(*limits); err != nil {
+	if err := cfg.SlackOptions.Limits.Apply(limits); err != nil {
 		return nil, err
 	}
 	return cmd.Flag.Args(), nil