add test for cli

gffutils/test/test_cli.py

@@ -0,0 +1,18 @@
+import subprocess as sp
+import gffutils
+from gffutils import example_filename, create, feature
+
+
+def test_issue_224():
+    fn = gffutils.example_filename("FBgn0031208.gtf")
+    sp.run(["gffutils-cli", "create", "--force", fn])
+    p = sp.run(
+        ["gffutils-cli", "children", fn + ".db", "FBgn0031208"],
+        check=True,
+        capture_output=True,
+        universal_newlines=True,
+    )
+    assert (
+        p.stdout.splitlines()[0]
+        == 'chr2L\tgffutils_derived\tgene\t7529\t9484\t.\t+\t.\tgene_id "FBgn0031208";'
+    )