From 518783a2b101c5dd98054882c763dbe7dd5742c8 Mon Sep 17 00:00:00 2001
From: Will McGugan <willmcgugan@gmail.com>
Date: Wed, 18 Jan 2023 14:51:50 +0000
Subject: [PATCH] added test

---
 src/textual/__init__.py |  1 +
 tests/test_version.py   | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)
 create mode 100644 tests/test_version.py

diff --git a/src/textual/__init__.py b/src/textual/__init__.py
index 30eb9c3e8..5f1db4820 100644
--- a/src/textual/__init__.py
+++ b/src/textual/__init__.py
@@ -16,6 +16,7 @@ LogCallable: TypeAlias = "Callable"
 
 
 def __getattr__(name: str) -> str:
+    """Lazily get the version from whatever API is available."""
     if name == "__version__":
         try:
             from importlib.metadata import version
diff --git a/tests/test_version.py b/tests/test_version.py
new file mode 100644
index 000000000..dfb0a4b8f
--- /dev/null
+++ b/tests/test_version.py
@@ -0,0 +1,41 @@
+import re
+
+# https://stackoverflow.com/questions/37972029/regex-to-match-pep440-compliant-version-strings
+VERSION_PATTERN = r"""
+    v?
+    (?:
+        (?:(?P<epoch>[0-9]+)!)?                           # epoch
+        (?P<release>[0-9]+(?:\.[0-9]+)*)                  # release segment
+        (?P<pre>                                          # pre-release
+            [-_\.]?
+            (?P<pre_l>(a|b|c|rc|alpha|beta|pre|preview))
+            [-_\.]?
+            (?P<pre_n>[0-9]+)?
+        )?
+        (?P<post>                                         # post release
+            (?:-(?P<post_n1>[0-9]+))
+            |
+            (?:
+                [-_\.]?
+                (?P<post_l>post|rev|r)
+                [-_\.]?
+                (?P<post_n2>[0-9]+)?
+            )
+        )?
+        (?P<dev>                                          # dev release
+            [-_\.]?
+            (?P<dev_l>dev)
+            [-_\.]?
+            (?P<dev_n>[0-9]+)?
+        )?
+    )
+    (?:\+(?P<local>[a-z0-9]+(?:[-_\.][a-z0-9]+)*))?       # local version
+"""
+
+
+def test_version():
+    import textual
+
+    version = textual.__version__
+    assert isinstance(version, str)
+    assert re.match(VERSION_PATTERN, version, re.VERBOSE) is not None