add tests for CLI

Signed-off-by: Michele Dolfi <dol@zurich.ibm.com>

tests/test_cli.py

@@ -0,0 +1,20 @@
+from typer.testing import CliRunner
+
+from docling.cli.main import app
+
+runner = CliRunner()
+
+
+def test_cli_help():
+    result = runner.invoke(app, ["--help"])
+    assert result.exit_code == 0
+
+
+def test_cli_version():
+    result = runner.invoke(app, ["--version"])
+    assert result.exit_code == 0
+
+
+def test_cli_convert():
+    result = runner.invoke(app, ["./tests/data/2305.03393v1-pg9.pdf"])
+    assert result.exit_code == 0