Feature help no selection 1036 (#1042)

* Added validation for --selected

* Added test for #999 (project_info) that I missed on last branch

tests/test_cli_export_projects.py

@@ -0,0 +1,23 @@
+"""Test that libraries containing projects are handled correctly, #999"""
+
+import os
+
+import pytest
+from click.testing import CliRunner
+
+from osxphotos.cli import export
+
+PHOTOS_DB_PROJECTS = "./tests/Test-iPhoto-Projects-10.15.7.photoslibrary"
+
+
+def test_export_projects():
+    """test basic export with library containing projects"""
+    runner = CliRunner()
+    cwd = os.getcwd()
+    # pylint: disable=not-context-manager
+    with runner.isolated_filesystem():
+        result = runner.invoke(
+            export, ["--library", os.path.join(cwd, PHOTOS_DB_PROJECTS), ".", "-V"]
+        )
+        assert result.exit_code == 0
+        assert "error: 0" in result.output