From b467258664af70a1650a9f24b237f8ab5ca86a4f Mon Sep 17 00:00:00 2001
From: Lunny Xiao <xiaolunwen@gmail.com>
Date: Thu, 11 Nov 2021 21:10:54 +0800
Subject: [PATCH] Support use io/fs.FS directly (#97)

---
 fs_embed.go | 30 ++++++++++++++++++
 fs_test.go  | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 121 insertions(+)
 create mode 100644 fs_test.go

diff --git a/fs_embed.go b/fs_embed.go
index 5dd2d2b..d5169db 100644
--- a/fs_embed.go
+++ b/fs_embed.go
@@ -1,9 +1,11 @@
+//go:build go1.16
 // +build go1.16
 
 package render
 
 import (
 	"embed"
+	"io"
 	"io/fs"
 	"path/filepath"
 )
@@ -29,3 +31,31 @@ func (e *EmbedFileSystem) Walk(root string, walkFn filepath.WalkFunc) error {
 		return walkFn(path, info, err)
 	})
 }
+
+type tmplFS struct {
+	fs.FS
+}
+
+func (tfs tmplFS) Walk(root string, walkFn filepath.WalkFunc) error {
+	return fs.WalkDir(tfs, root, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		info, err := d.Info()
+		return walkFn(path, info, err)
+	})
+}
+
+func (tfs tmplFS) ReadFile(filename string) ([]byte, error) {
+	f, err := tfs.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	return io.ReadAll(f)
+}
+
+// FS converts io/fs.FS to FileSystem
+func FS(oriFS fs.FS) FileSystem {
+	return tmplFS{oriFS}
+}
diff --git a/fs_test.go b/fs_test.go
new file mode 100644
index 0000000..ebbf067
--- /dev/null
+++ b/fs_test.go
@@ -0,0 +1,91 @@
+//go:build go1.16
+// +build go1.16
+
+package render
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+)
+
+func TestIOFSEmbedTemplateLookup(t *testing.T) {
+	baseDir := "testdata/template-dir-test"
+	fname0Rel := "0"
+	fname1Rel := "subdir/1"
+	fnameShouldParsedRel := "dedicated.tmpl/notbad"
+	dirShouldNotParsedRel := "dedicated"
+
+	r := New(Options{
+		Directory:  baseDir,
+		Extensions: []string{".tmpl", ".html"},
+		FileSystem: FS(EmbedFixtures),
+	})
+
+	expect(t, r.TemplateLookup(fname1Rel) != nil, true)
+	expect(t, r.TemplateLookup(fname0Rel) != nil, true)
+	expect(t, r.TemplateLookup(fnameShouldParsedRel) != nil, true)
+	expect(t, r.TemplateLookup(dirShouldNotParsedRel) == nil, true)
+}
+
+func TestIOFSDirTemplateLookup(t *testing.T) {
+	baseDir := "testdata/template-dir-test"
+	fname0Rel := "0"
+	fname1Rel := "subdir/1"
+	fnameShouldParsedRel := "dedicated.tmpl/notbad"
+	dirShouldNotParsedRel := "dedicated"
+
+	r := New(Options{
+		Directory:  ".",
+		Extensions: []string{".tmpl", ".html"},
+		FileSystem: FS(os.DirFS(baseDir)),
+	})
+
+	expect(t, r.TemplateLookup(fname1Rel) != nil, true)
+	expect(t, r.TemplateLookup(fname0Rel) != nil, true)
+	expect(t, r.TemplateLookup(fnameShouldParsedRel) != nil, true)
+	expect(t, r.TemplateLookup(dirShouldNotParsedRel) == nil, true)
+}
+
+func TestIOFSEmbedHTMLBasic(t *testing.T) {
+	render := New(Options{
+		Directory:  "testdata/basic",
+		FileSystem: FS(EmbedFixtures),
+	})
+
+	var err error
+	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		err = render.HTML(w, http.StatusOK, "hello", "gophers")
+	})
+
+	res := httptest.NewRecorder()
+	req, _ := http.NewRequestWithContext(ctx, "GET", "/foo", nil)
+	h.ServeHTTP(res, req)
+
+	expectNil(t, err)
+	expect(t, res.Code, 200)
+	expect(t, res.Header().Get(ContentType), ContentHTML+"; charset=UTF-8")
+	expect(t, res.Body.String(), "<h1>Hello gophers</h1>\n")
+}
+
+func TestIOFSDirHTMLBasic(t *testing.T) {
+	render := New(Options{
+		Directory:  ".",
+		FileSystem: FS(os.DirFS("testdata/basic")),
+	})
+
+	var err error
+	h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		err = render.HTML(w, http.StatusOK, "hello", "gophers")
+	})
+
+	res := httptest.NewRecorder()
+	req, _ := http.NewRequestWithContext(ctx, "GET", "/foo", nil)
+	h.ServeHTTP(res, req)
+
+	expectNil(t, err)
+	expect(t, res.Code, 200)
+	expect(t, res.Header().Get(ContentType), ContentHTML+"; charset=UTF-8")
+	expect(t, res.Body.String(), "<h1>Hello gophers</h1>\n")
+}