Return bytes from conversion functions

This will allow more re-use

cmd/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"fmt"
 	"log"
 	"os"
@@ -14,20 +15,28 @@ import (
 func convert(story squire.Story, format string) {
 	fmt.Println("Converting to", format)
 
+	// TODO: make this configurable
+	const fileNameBase = "output"
+
 	var err error
+	var buf bytes.Buffer
+	var extension = "html"
 
 	switch {
 	case format == "html":
-		err = squire.ConvertToHtml(story, true)
+		buf, err = squire.ConvertToHtml(story, true)
 	case format == "html-inner":
-		err = squire.ConvertToHtml(story, false)
+		buf, err = squire.ConvertToHtml(story, false)
 	case format == "epub":
-		err = squire.ConvertToEpub(story)
+		extension = "epub"
+		buf, err = squire.ConvertToEpub(story)
 	default:
 		fmt.Println("Invalid conversion format. Allowed options are 'html', 'html-inner', or 'epub'")
 	}
 
-	if err != nil {
+	if err == nil {
+		os.WriteFile(fileNameBase+"."+extension, buf.Bytes(), 0644)
+	} else {
 		log.Fatalf("error converting to %s: %v", format, err)
 	}
 }

pkg/convert.go

@@ -1,10 +1,10 @@
 package squire
 
 import (
+	"bytes"
 	_ "embed"
 	"encoding/base64"
 	"fmt"
-	"os"
 	"strings"
 
 	"github.com/go-shiori/go-epub"
@@ -56,7 +56,7 @@ func sortedChapters(chapters map[string]Chapter) []Chapter {
 	return sorted
 }
 
-func ConvertToHtml(story Story, full bool) error {
+func ConvertToHtml(story Story, full bool) (bytes.Buffer, error) {
 	html := ""
 
 	if full {
@@ -90,22 +90,26 @@ func ConvertToHtml(story Story, full bool) error {
 		html += "</body>\n</html>"
 	}
 
-	return os.WriteFile(story.Title+".html", []byte(html), 0644)
+	buffer := bytes.NewBufferString(html)
+
+	return *buffer, nil
 }
 
-func ConvertToEpub(story Story) error {
+func ConvertToEpub(story Story) (bytes.Buffer, error) {
+	var buffer bytes.Buffer
+
 	book, err := epub.NewEpub(story.Title)
 
 	if err != nil {
-		return err
+		return buffer, err
 	}
 
 	book.SetAuthor(story.Author)
 
 	cssPath, err := book.AddCSS(cssContent(), "")
 
 	if err != nil {
-		return err
+		return buffer, err
 	}
 
 	for _, chapter := range sortedChapters(story.Chapters) {
@@ -126,9 +130,15 @@ func ConvertToEpub(story Story) error {
 		_, err = book.AddSection(content, chapter.Title, chapter.Id, cssPath)
 
 		if err != nil {
-			return err
+			return buffer, err
 		}
 	}
 
-	return book.Write(story.Title + ".epub")
+	_, err = book.WriteTo(&buffer)
+
+	if err != nil {
+		return buffer, err
+	}
+
+	return buffer, nil
 }

pkg/convert_test.go

@@ -24,13 +24,7 @@ func TestConvertStory(t *testing.T) {
 			t.Fatal(err)
 		}
 
-		err = ConvertToHtml(story, true)
-
-		if err != nil {
-			t.Fatal(err)
-		}
-
-		output, err := os.ReadFile(story.Title + ".html")
+		buf, err := ConvertToHtml(story, true)
 
 		if err != nil {
 			t.Fatal(err)
@@ -42,7 +36,7 @@ func TestConvertStory(t *testing.T) {
 			t.Fatal(err)
 		}
 
-		assertEqual(t, strings.TrimSpace(string(output)), strings.TrimSpace(string(expected)))
+		assertEqual(t, strings.TrimSpace(buf.String()), strings.TrimSpace(string(expected)))
 	})
 
 	t.Run("Converting a story to inner-html", func(t *testing.T) {
@@ -58,13 +52,7 @@ func TestConvertStory(t *testing.T) {
 			t.Fatal(err)
 		}
 
-		err = ConvertToHtml(story, false)
-
-		if err != nil {
-			t.Fatal(err)
-		}
-
-		output, err := os.ReadFile(story.Title + ".html")
+		buf, err := ConvertToHtml(story, false)
 
 		if err != nil {
 			t.Fatal(err)
@@ -76,6 +64,6 @@ func TestConvertStory(t *testing.T) {
 			t.Fatal(err)
 		}
 
-		assertEqual(t, strings.TrimSpace(string(output)), strings.TrimSpace(string(expected)))
+		assertEqual(t, strings.TrimSpace(buf.String()), strings.TrimSpace(string(expected)))
 	})
 }