feat: declare API errors and authentication with developer tooling

examples/userService/internal/middleware/auth_test.go

@@ -33,3 +33,31 @@ func TestAuthFailsClosedAndDoesNotLeakKey(t *testing.T) {
 		}
 	}
 }
+
+func TestReadOnlyTokenCanReadButCannotWrite(t *testing.T) {
+	admin := "admin-012345678901234567890123456789"
+	read := "read-012345678901234567890123456789"
+	t.Setenv("USER_SERVICE_API_TOKEN", admin)
+	t.Setenv("USER_SERVICE_READ_TOKEN", read)
+	middleware, err := NewAuthFromEnv()
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, method := range []string{"GET", "POST", "PUT", "DELETE"} {
+		called := false
+		r := httptest.NewRequest(method, "/api/v1/users", nil)
+		r.Header.Set("Authorization", "Bearer "+read)
+		err = middleware(func(*httpx.Context) error { called = true; return nil })(httpx.NewContext(r, httptest.NewRecorder(), nil))
+		if method == "GET" {
+			if err != nil || !called {
+				t.Fatal("read token rejected on GET")
+			}
+		} else if err == nil || called || apierrors.From(err).Status != 403 {
+			t.Fatal("read token reached a write")
+		}
+	}
+	t.Setenv("USER_SERVICE_READ_TOKEN", admin)
+	if _, err = NewAuthFromEnv(); err == nil {
+		t.Fatal("identical privilege tokens accepted")
+	}
+}