catch if base plugin is not registered

converter/convert.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"errors"
 	"io"
+	"slices"
 	"strings"
 
 	"golang.org/x/net/html"
@@ -40,7 +41,8 @@ func (conv *Converter) getError() error {
 	return conv.err
 }
 
-var errNoRenderHandlers = errors.New("no render handlers are registered. did you forget to register the commonmark plugin?")
+var errNoRenderHandlers = errors.New(`no render handlers are registered. did you forget to register the "commonmark" and "base" plugins?`)
+var errBasePluginMissing = errors.New(`you registered the "commonmark" plugin but the "base" plugin is also required`)
 
 // ConvertNode converts a `*html.Node` to a markdown byte slice.
 //
@@ -65,11 +67,15 @@ func (conv *Converter) ConvertNode(doc *html.Node, opts ...convertOptionFunc) ([
 	// If there are no render handlers registered this is
 	// usually a user error - since people want the Commonmark Plugin in 99% of cases.
 	if len(conv.getRenderHandlers()) == 0 {
-		// TODO: Add Name() to the interface & check for the presence of *both* the Base & Commonmark Plugin
-		// TODO: What if just the base plugin is registered?
 		return nil, errNoRenderHandlers
 	}
 
+	containsCommonmark := slices.Contains(conv.registeredPlugins, "commonmark")
+	containsBase := slices.Contains(conv.registeredPlugins, "base")
+	if containsCommonmark && !containsBase {
+		return nil, errBasePluginMissing
+	}
+
 	// - - - - - - - - - - - - - - - - - - - //
 
 	state := newGlobalState()

converter/convert_test.go

@@ -6,6 +6,7 @@ import (
 	"github.com/JohannesKaufmann/dom"
 	"github.com/JohannesKaufmann/html-to-markdown/v2/converter"
 	"github.com/JohannesKaufmann/html-to-markdown/v2/plugin/base"
+	"github.com/JohannesKaufmann/html-to-markdown/v2/plugin/commonmark"
 	"golang.org/x/net/html"
 )
 
@@ -61,7 +62,7 @@ func TestConvertString_ErrNoRenderHandlers(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected an error")
 	}
-	if err.Error() != "no render handlers are registered. did you forget to register the commonmark plugin?" {
+	if err.Error() != `no render handlers are registered. did you forget to register the "commonmark" and "base" plugins?` {
 		t.Fatal("expected a different error but got", err)
 	}
 
@@ -78,6 +79,22 @@ func TestConvertString_ErrNoRenderHandlers(t *testing.T) {
 	}
 }
 
+func TestConvertString_ErrBasePluginMissing(t *testing.T) {
+	conv := converter.NewConverter(
+		converter.WithPlugins(
+			commonmark.NewCommonmarkPlugin(),
+		),
+	)
+
+	_, err := conv.ConvertString("<strong>bold text</strong>")
+	if err == nil {
+		t.Fatal("expected an error")
+	}
+	if err.Error() != `you registered the "commonmark" plugin but the "base" plugin is also required` {
+		t.Fatal("expected a different error but got", err)
+	}
+}
+
 func TestWithEscapeMode(t *testing.T) {
 	mockRenderer := func(ctx converter.Context, w converter.Writer, n *html.Node) converter.RenderStatus {
 		return converter.RenderTryNext

converter/converter.go

@@ -7,6 +7,8 @@ type Converter struct {
 
 	err error
 
+	registeredPlugins []string
+
 	preRenderHandlers  prioritizedSlice[HandlePreRenderFunc]
 	renderHandlers     prioritizedSlice[HandleRenderFunc]
 	postRenderHandlers prioritizedSlice[HandlePostRenderFunc]

converter/plugin.go

@@ -1,8 +1,13 @@
 package converter
 
+import "errors"
+
 // Plugin can be used to extends functionality beyond what
 // is offered by commonmark.
 type Plugin interface {
+	// The public name of the plugin, e.g. "strikethrough"
+	Name() string
+
 	// Init is called to initialize the plugin. It can be used to
 	// *validate* the arguments and *register* the rules.
 	Init(conv *Converter) error
@@ -12,6 +17,12 @@ type Plugin interface {
 func WithPlugins(plugins ...Plugin) converterOption {
 	return func(c *Converter) error {
 		for _, plugin := range plugins {
+			pluginName := plugin.Name()
+			if pluginName == "" {
+				return errors.New("the plugin has no name")
+			}
+			c.registeredPlugins = append(c.registeredPlugins, pluginName)
+
 			err := plugin.Init(c)
 			if err != nil {
 				return err

plugin/base/base.go

@@ -24,6 +24,9 @@ func NewBasePlugin() converter.Plugin {
 	return &base
 }
 
+func (s *base) Name() string {
+	return "base"
+}
 func (b *base) Init(conv *converter.Converter) error {
 	conv.Register.TagType("#comment", converter.TagTypeRemove, converter.PriorityStandard)
 	conv.Register.TagType("head", converter.TagTypeRemove, converter.PriorityStandard)

plugin/commonmark/commonmark.go

@@ -102,6 +102,9 @@ func NewCommonmarkPlugin(opts ...OptionFunc) converter.Plugin {
 	return &cm
 }
 
+func (s *commonmark) Name() string {
+	return "commonmark"
+}
 func (cm *commonmark) Init(conv *converter.Converter) error {
 	if err := validateConfig(&cm.config); err != nil {
 		return err

plugin/strikethrough/strikethrough.go

@@ -38,6 +38,9 @@ func NewStrikethroughPlugin(opts ...option) converter.Plugin {
 	return plugin
 }
 
+func (s *strikethroughPlugin) Name() string {
+	return "strikethrough"
+}
 func (s *strikethroughPlugin) Init(conv *converter.Converter) error {
 	conv.Register.PreRenderer(s.handlePreRender, converter.PriorityStandard)