TST: Add a test for _build

arch/meson.build

@@ -71,6 +71,7 @@ subdir('univariate')
 
 subdirs_list = [
     '__future__',
+    '_build',
     'bootstrap',
     'compat',
     'covariance',

arch/tests/test_build.py

@@ -0,0 +1,36 @@
+import tempfile
+
+import pytest
+
+from arch import __version__, version_tuple
+
+try:
+    from arch._build.git_version import get_version, write_version_file
+
+    HAS_SETUPTOOLS_SCM = True
+except ImportError:
+    HAS_SETUPTOOLS_SCM = False
+
+
+@pytest.mark.skipif(not HAS_SETUPTOOLS_SCM, reason="setuptools_scm is not installed")
+def test_get_version():
+    try:
+        version, version_fields = get_version()
+
+        assert isinstance(version, str)
+        assert isinstance(version_fields, tuple)
+        assert all(isinstance(v, (int, str)) for v in version_fields)
+    except LookupError:
+        pytest.skip("No git repository found")
+
+
+@pytest.mark.skipif(not HAS_SETUPTOOLS_SCM, reason="setuptools_scm is not installed")
+def test_write_version_file():
+    with tempfile.NamedTemporaryFile(delete=False) as tmpfile:
+
+        write_version_file(tmpfile.name, __version__, version_tuple)
+        with open(tmpfile.name, "r") as f:
+            content = f.read()
+
+            assert f"__version__ = version = '{__version__}'" in content
+            assert f"__version_tuple__ = version_tuple = {version_tuple}" in content