fix: give helpful errors on missing positional arguments

give some helpful hints if a user does not path the appropriate number
of position arguments to the CLI.

Author: toumorokoshi

internal/service/service.go

@@ -28,12 +28,12 @@ func NewService(serviceDefinition ServiceDefinition, headers map[string]string)
 
 func (s *Service) ExecuteCommand(args []string) (string, error) {
 	if len(args) == 0 || args[0] == "--help" {
-		return s.ListResources(), nil
+		return s.PrintHelp(), nil
 	}
 	resource := args[0]
 	r, err := s.GetResource(resource)
 	if err != nil {
-		return "", fmt.Errorf("%v\n%v", err, s.ListResources())
+		return "", fmt.Errorf("%v\n%v", err, s.PrintHelp())
 	}
 	req, err := r.ExecuteCommand(args)
 	if err != nil {
@@ -82,14 +82,16 @@ func (s *Service) doRequest(r *http.Request) (string, error) {
 	return prettyJSON.String(), nil
 }
 
-func (s *Service) ListResources() string {
+func (s *Service) PrintHelp() string {
 	var resources []string
 	for singular := range s.Resources {
 		resources = append(resources, singular)
 	}
 	sort.Strings(resources)
 
 	var output strings.Builder
+	output.WriteString("Usage: [resource] [method] [flags]\n\n")
+	output.WriteString("Command group for " + s.ServerURL + "\n\n")
 	output.WriteString("Available resources:\n")
 	for _, r := range resources {
 		output.WriteString(fmt.Sprintf("  - %s\n", r))

internal/service/service_definition.go

@@ -131,7 +131,7 @@ func GetServiceDefinition(api *openapi.OpenAPI, pathPrefix string) (*ServiceDefi
 func (s *ServiceDefinition) GetResource(resource string) (*Resource, error) {
 	r, ok := (*s).Resources[resource]
 	if !ok {
-		return nil, fmt.Errorf("resource %q not found", resource)
+		return nil, fmt.Errorf("Resource %s not found.", resource)
 	}
 	return r, nil
 }

internal/service/service_test.go

@@ -1 +1,46 @@
 package service
+
+import (
+	"testing"
+)
+
+func TestService_ExecuteCommand_ListResources(t *testing.T) {
+	// Test setup
+	svc := NewService(ServiceDefinition{
+		ServerURL: "http://test.com",
+		Resources: map[string]*Resource{
+			"user":    {},
+			"post":    {},
+			"comment": {},
+		},
+	}, nil)
+
+	tests := []struct {
+		name     string
+		args     []string
+		expected string
+	}{
+		{
+			name:     "no arguments",
+			args:     []string{},
+			expected: "Available resources:\n  - comment\n  - post\n  - user\n",
+		},
+		{
+			name:     "help flag",
+			args:     []string{"--help"},
+			expected: "Available resources:\n  - comment\n  - post\n  - user\n",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, err := svc.ExecuteCommand(tt.args)
+			if err != nil {
+				t.Errorf("ExecuteCommand() error = %v, expected no error", err)
+			}
+			if result != tt.expected {
+				t.Errorf("ExecuteCommand() = %v, expected %v", result, tt.expected)
+			}
+		})
+	}
+}