test: add test for new_common_exported_apps TOML generation

Add a test that verifies the mock exported apps command generates
valid TOML that can be parsed by the same DesktopFiles deserializer
used for real output. This ensures the NullWorking store type will
work correctly with the application listing feature.

Author: ranfdev

src/backends/distrobox/distrobox.rs

@@ -1323,4 +1323,56 @@ Categories=Utility;Security;";
 17 | Crystal Linux | Created 2 minutes ago | docker.io/library/crystal-linux:latest\n"
         );
     }
+
+    #[test]
+    fn stub_exported_apps_generates_valid_toml() {
+        // Verify that new_common_exported_apps generates valid TOML that can be parsed
+        let exported_apps = DistroboxCommandRunnerResponse::new_common_exported_apps();
+        let commands = exported_apps.to_commands();
+
+        // Find the command that should contain TOML output (distrobox enter ... sh -c ...)
+        let toml_command = commands
+            .iter()
+            .find(|(cmd, _)| {
+                cmd.program.to_string_lossy().contains("distrobox")
+                    && cmd.args.iter().any(|arg| arg.to_string_lossy() == "enter")
+            })
+            .expect("Should have a TOML-generating command");
+
+        let toml_output = toml_command.1().expect("Should generate output");
+
+        // Verify the TOML is parseable
+        let desktop_files: DesktopFiles = toml::from_str(&toml_output)
+            .expect("Generated TOML should be valid and parseable");
+
+        // Verify home_dir is set
+        assert_eq!(
+            desktop_files.home_dir.to_string_lossy(),
+            "/home/me",
+            "home_dir should be /home/me"
+        );
+
+        // Verify we have system files (the mock apps should be in system)
+        assert!(
+            !desktop_files.system.is_empty(),
+            "Should have system desktop files"
+        );
+
+        // Verify all system files are valid desktop entries
+        for (path, content) in &desktop_files.system {
+            assert!(
+                path.to_string_lossy().ends_with(".desktop"),
+                "Path should end with .desktop: {:?}",
+                path
+            );
+            assert!(
+                content.contains("[Desktop Entry]"),
+                "Content should be a valid desktop entry"
+            );
+            assert!(
+                content.contains("Name="),
+                "Content should have a Name field"
+            );
+        }
+    }
 }