api: Add go files

I know this is a huge commit, but I can't be bothered to check
this in part by part.

api/comment_domain_get_test.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"testing"
+	"time"
+)
+
+func TestCommentDomainGetBasics(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	commentHex, _ := commentNew("temp-commenter-hex", "example.com", "/path.html", "root", "**foo**", "approved", time.Now().UTC())
+
+	domain, err := commentDomainGet(commentHex)
+	if err != nil {
+		t.Errorf("unexpected error getting domain by hex: %v", err)
+		return
+	}
+
+	if domain != "example.com" {
+		t.Errorf("expected domain = example.com got domain = %s", domain)
+		return
+	}
+}
+
+func TestCommentDomainGetEmpty(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	if _, err := commentDomainGet(""); err == nil {
+		t.Errorf("expected error not found getting domain with empty commentHex")
+		return
+	}
+}