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/domain_new_test.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"testing"
+)
+
+func TestDomainNewBasics(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	if err := domainNew("temp-owner-hex", "Example", "example.com"); err != nil {
+		t.Errorf("unexpected error creating domain: %v", err)
+		return
+	}
+}
+
+func TestDomainNewClash(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	if err := domainNew("temp-owner-hex", "Example", "example.com"); err != nil {
+		t.Errorf("unexpected error creating domain: %v", err)
+		return
+	}
+
+	if err := domainNew("temp-owner-hex", "Example 2", "example.com"); err == nil {
+		t.Errorf("expected error not found when creating with clashing domain")
+		return
+	}
+}
+
+func TestDomainNewEmpty(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	if err := domainNew("temp-owner-hex", "Example", ""); err == nil {
+		t.Errorf("expected error not found when creating with emtpy domain")
+		return
+	}
+
+	if err := domainNew("", "", ""); err == nil {
+		t.Errorf("expected error not found when creating with emtpy everything")
+		return
+	}
+}