Added unit tests

tests/providers/local_tests.rs

@@ -0,0 +1,12 @@
+use gman::providers::local::LocalProviderConfig;
+
+
+#[test]
+fn test_local_provider_config_default() {
+    let config = LocalProviderConfig::default();
+    let expected_path = dirs::home_dir()
+        .map(|p| p.join(".gman_vault"))
+        .and_then(|p| p.to_str().map(|s| s.to_string()))
+        .unwrap_or_else(|| ".gman_vault".into());
+    assert_eq!(config.vault_path, expected_path);
+}