Assert newlines in helptext

dandi/tests/test_helptext.py

@@ -0,0 +1,18 @@
+import pytest
+
+import subprocess
+
+
+def get_helptext(command):
+    result = subprocess.run([*command, '--help'], stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
+    return result.stdout
+
+def test_resource_identifier_helptext():
+    # The \n chars must be included for correct rendering
+    correct = "Accepted resource identifier patterns:\n   - DANDI:<dandiset id>[/<version>]\n"
+
+    ls_helptext = get_helptext(['dandi', 'ls'])
+    assert correct in ls_helptext
+
+    download_helptext = get_helptext(['dandi', 'download'])
+    assert correct in download_helptext