feat: render Markdown, mathematics and Mermaid diagrams server-side

internal/markdown/parse_test.go

@@ -0,0 +1,69 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: MIT
+
+package markdown
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestDeterministicOutput(t *testing.T) {
+	source := []byte("# Title\n\nText with < and &.\n\n- one\n  - nested\n\n> quoted\n\n" +
+		"```go\nx := 1\n```\n\n[ref]: /url \"title\"\n")
+	first := RenderHTML(source)
+	for i := range 10 {
+		if next := RenderHTML(source); !bytes.Equal(first, next) {
+			t.Fatalf("render %d differs:\nfirst: %q\nnext:  %q", i, first, next)
+		}
+	}
+}
+
+func TestReferenceNormalisation(t *testing.T) {
+	doc := Parse([]byte("[Foo Bar]: /first\n[FOO\t bar]: /second\n"))
+	if len(doc.refs) != 1 {
+		t.Fatalf("got %d references, want 1", len(doc.refs))
+	}
+	ref, ok := doc.refs["foo bar"]
+	if !ok {
+		t.Fatalf("no reference under the normalised label \"foo bar\"")
+	}
+	if ref.destination != "/first" {
+		t.Errorf("destination = %q, want \"/first\": the first definition wins", ref.destination)
+	}
+}
+
+func TestReferenceTitleKept(t *testing.T) {
+	doc := Parse([]byte("[foo]: /url 'the title'\n"))
+	ref, ok := doc.refs["foo"]
+	if !ok {
+		t.Fatal("no reference recorded")
+	}
+	if !ref.hasTitle || ref.title != "the title" {
+		t.Errorf("title = %q with hasTitle %v, want \"the title\" with hasTitle", ref.title, ref.hasTitle)
+	}
+}
+
+func TestJunkAfterTitleIsNotADefinition(t *testing.T) {
+	doc := Parse([]byte("[foo]: /url \"title\" ok\n"))
+	if len(doc.refs) != 0 {
+		t.Errorf("got %d references, want 0", len(doc.refs))
+	}
+	if len(doc.children) != 1 || doc.children[0].kind != kindParagraph {
+		t.Fatalf("the line should stay a paragraph")
+	}
+}
+
+func TestBacktickInfoStringRejectsFence(t *testing.T) {
+	doc := Parse([]byte("``` aaa ```\n"))
+	if len(doc.children) != 1 || doc.children[0].kind != kindParagraph {
+		t.Fatalf("the line should stay a paragraph, got %d children", len(doc.children))
+	}
+}
+
+func TestParseEmptyDocument(t *testing.T) {
+	doc := Parse(nil)
+	if doc.kind != kindDocument || len(doc.children) != 0 {
+		t.Errorf("Parse(nil) should give an empty document")
+	}
+}