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_get_test.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"testing"
+)
+
+func TestDomainGetBasics(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	domainNew("temp-owner-hex", "Example", "example.com")
+
+	d, err := domainGet("example.com")
+	if err != nil {
+		t.Errorf("unexpected error getting domain: %v", err)
+		return
+	}
+
+	if d.Name != "Example" {
+		t.Errorf("expected name=Example got name=%s", d.Name)
+		return
+	}
+}
+
+func TestDomainGetEmpty(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	if _, err := domainGet(""); err == nil {
+		t.Errorf("expected error not found when getting with empty domain")
+		return
+	}
+}
+
+func TestDomainGetDNE(t *testing.T) {
+	failTestOnError(t, setupTestEnv())
+
+	if _, err := domainGet("example.com"); err == nil {
+		t.Errorf("expected error not found when getting non-existant domain")
+		return
+	}
+}