Add OpenGraph gomponent (#1)

gallery.go

@@ -1 +1,18 @@
-package template
+package gallery
+
+import (
+	. "github.com/maragudk/gomponents"
+	. "github.com/maragudk/gomponents/html"
+)
+
+// OpenGraph tags for a website.
+// Title is always set, og:description, og:image, and og:url only if non-empty.
+func OpenGraph(title, description, image, url string) Node {
+	return Group([]Node{
+		Meta(Attr("property", "og:type"), Content("website")),
+		Meta(Attr("property", "og:title"), Content(title)),
+		If(description != "", Meta(Attr("property", "og:description"), Content(description))),
+		If(image != "", Meta(Attr("property", "og:image"), Content(image))),
+		If(url != "", Meta(Attr("property", "og:url"), Content(url))),
+	})
+}

gallery_test.go

@@ -0,0 +1,28 @@
+package gallery_test
+
+import (
+	"os"
+	"testing"
+
+	gallery "maragu.dev/gomponents-gallery"
+	"maragu.dev/gomponents-gallery/internal/assert"
+)
+
+func TestOpenGraph(t *testing.T) {
+	t.Run("can generate OpenGraph tags", func(t *testing.T) {
+		og := gallery.OpenGraph("Partyhats for everyone!", "Bring your own glitter.", "https://www.example.com/partyhat.jpg", "https://www.example.com/partyhats-for-everyone")
+		assert.Equal(t,
+			`<meta property="og:type" content="website"><meta property="og:title" content="Partyhats for everyone!"><meta property="og:description" content="Bring your own glitter."><meta property="og:image" content="https://www.example.com/partyhat.jpg"><meta property="og:url" content="https://www.example.com/partyhats-for-everyone">`,
+			og)
+	})
+}
+
+func ExampleOpenGraph() {
+	og := gallery.OpenGraph(
+		"Partyhats for everyone!",
+		"Bring your own glitter.",
+		"https://www.example.com/partyhat.jpg",
+		"https://www.example.com/partyhats-for-everyone")
+	_ = og.Render(os.Stdout)
+	// Output: <meta property="og:type" content="website"><meta property="og:title" content="Partyhats for everyone!"><meta property="og:description" content="Bring your own glitter."><meta property="og:image" content="https://www.example.com/partyhat.jpg"><meta property="og:url" content="https://www.example.com/partyhats-for-everyone">
+}

go.mod

@@ -1,3 +1,5 @@
-module template
+module maragu.dev/gomponents-gallery
 
-go 1.23
+go 1.18
+
+require github.com/maragudk/gomponents v0.21.0

go.sum

@@ -0,0 +1,2 @@
+github.com/maragudk/gomponents v0.21.0 h1:s0QbrirP8/rH1P4kqN48DN2zjvpk9wHkSqi4+xp99SQ=
+github.com/maragudk/gomponents v0.21.0/go.mod h1:nHkNnZL6ODgMBeJhrZjkMHVvNdoYsfmpKB2/hjdQ0Hg=

internal/assert/assert.go

@@ -0,0 +1,29 @@
+// Package assert provides testing helpers.
+package assert
+
+import (
+	"strings"
+	"testing"
+
+	g "github.com/maragudk/gomponents"
+)
+
+// Equal checks for equality between the given expected string and the rendered Node string.
+func Equal(t *testing.T, expected string, actual g.Node) {
+	t.Helper()
+
+	var b strings.Builder
+	_ = actual.Render(&b)
+	if expected != b.String() {
+		t.Fatalf(`expected "%v" but got "%v"`, expected, b.String())
+	}
+}
+
+// Error checks for a non-nil error.
+func Error(t *testing.T, err error) {
+	t.Helper()
+
+	if err == nil {
+		t.Fatal("error is nil")
+	}
+}