diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 0000000..578ba67
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,34 @@
+name: Run Python Tests for Spaces
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        os: [ubuntu-16.04, ubuntu-18.04, ubuntu-20.04, macos-latest]
+        python-version: [3.6, 3.7, 3.8, 3.9]
+
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Test Search Space
+	run: |
+          python -m pip install pytest
+          echo $PWD
+	  ls
+          python --version
+          python -m pytest AutoDL-Projects/tests --durations=0
+	
diff --git a/.latent-data/NATS-Bench b/.latent-data/NATS-Bench
index 51187c1..fbfcba7 160000
--- a/.latent-data/NATS-Bench
+++ b/.latent-data/NATS-Bench
@@ -1 +1 @@
-Subproject commit 51187c1e9152ff79b02b11c80bca0b03b402a7e5
+Subproject commit fbfcba7eb3ad19e862eca32ee0bb3195f1a8a9ef
diff --git a/lib/spaces/__init__.py b/lib/spaces/__init__.py
index 792d600..5550320 100644
--- a/lib/spaces/__init__.py
+++ b/lib/spaces/__init__.py
@@ -1 +1,7 @@
-#
+#####################################################
+# Copyright (c) Xuanyi Dong [GitHub D-X-Y], 2021.01 #
+#####################################################
+# Define complex searc space for AutoDL             #
+#####################################################
+
+from .basic_space import Categorical
diff --git a/lib/spaces/basic_space.py b/lib/spaces/basic_space.py
new file mode 100644
index 0000000..3f04020
--- /dev/null
+++ b/lib/spaces/basic_space.py
@@ -0,0 +1,33 @@
+#####################################################
+# Copyright (c) Xuanyi Dong [GitHub D-X-Y], 2021.01 #
+#####################################################
+
+import abc
+import random
+
+
+class Space(metaclass=abc.ABCMeta):
+    @abc.abstractmethod
+    def random(self):
+        raise NotImplementedError
+
+    @abc.abstractmethod
+    def __repr__(self):
+        raise NotImplementedError
+
+
+class Categorical(Space):
+    def __init__(self, *data):
+        self._candidates = [*data]
+
+    def __getitem__(self, index):
+        return self._candidates[index]
+
+    def __len__(self):
+        return len(self._candidates)
+
+    def __repr__(self):
+        return "{name:}(candidates={cs:})".format(name=self.__class__.__name__, cs=self._candidates)
+
+    def random(self):
+        return random.choice(self._candidates)
diff --git a/tests/test_basic.py b/tests/test_basic.py
new file mode 100644
index 0000000..6757e3a
--- /dev/null
+++ b/tests/test_basic.py
@@ -0,0 +1,22 @@
+#####################################################
+# Copyright (c) Xuanyi Dong [GitHub D-X-Y], 2021.03 #
+#####################################################
+import sys
+import unittest
+import pytest
+from pathlib import Path
+
+lib_dir = (Path(__file__).parent / ".." / "lib").resolve()
+print("library path: {:}".format(lib_dir))
+if str(lib_dir) not in sys.path:
+    sys.path.insert(0, str(lib_dir))
+
+from spaces import Categorical
+
+
+class TestBasicSpace(unittest.TestCase):
+    def test_categorical(self):
+        space = Categorical(1, 2, 3, 4)
+        for i in range(4):
+            self.assertEqual(space[i], i + 1)
+        self.assertEqual("Categorical(candidates=[1, 2, 3, 4])", str(space))