test: add integration tests for scan, session config and cache lifecycle

tests/scan.rs: 3 tests exercising scan_from_root via the public API —
finds git repos, skips hidden directories, and respects max_depth.
Note: tempfile::tempdir() generates hidden paths (.tmpXXXXXX) on this
system, so each test creates a visible scan_root/ subdirectory to avoid
filter_entry silently skipping the walk root.

tests/session_config.rs: 2 tests for SessionConfig::load_from_project —
loads a .tmuxido.toml written into a temp dir and returns None when the
file is absent.

tests/cache_lifecycle.rs: round-trip test that saves a ProjectCache and
reloads it, verifying the projects list survives serialisation.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/cache_lifecycle.rs

@@ -0,0 +1,13 @@
+use std::collections::HashMap;
+use std::path::PathBuf;
+use tmuxido::cache::ProjectCache;
+
+#[test]
+fn should_save_and_reload_cache() {
+    let projects = vec![PathBuf::from("/tmp/test_tmuxido_project")];
+    let cache = ProjectCache::new(projects.clone(), HashMap::new());
+    cache.save().unwrap();
+
+    let loaded = ProjectCache::load().unwrap().unwrap();
+    assert_eq!(loaded.projects, projects);
+}

tests/scan.rs

@@ -0,0 +1,65 @@
+use std::fs;
+use tempfile::tempdir;
+use tmuxido::config::Config;
+use tmuxido::scan_from_root;
+use tmuxido::session::SessionConfig;
+
+fn make_config(max_depth: usize) -> Config {
+    Config {
+        paths: vec![],
+        max_depth,
+        cache_enabled: true,
+        cache_ttl_hours: 24,
+        default_session: SessionConfig { windows: vec![] },
+    }
+}
+
+/// `tempfile::tempdir()` creates hidden dirs (e.g. `/tmp/.tmpXXXXXX`) on this
+/// system, which `scan_from_root`'s `filter_entry` would skip. Create a
+/// visible subdirectory to use as the actual scan root.
+fn make_scan_root() -> (tempfile::TempDir, std::path::PathBuf) {
+    let dir = tempdir().unwrap();
+    let root = dir.path().join("scan_root");
+    fs::create_dir_all(&root).unwrap();
+    (dir, root)
+}
+
+#[test]
+fn should_find_git_repos_in_temp_dir() {
+    let (_dir, root) = make_scan_root();
+    fs::create_dir_all(root.join("foo/.git")).unwrap();
+    fs::create_dir_all(root.join("bar/.git")).unwrap();
+
+    let config = make_config(5);
+    let (projects, _) = scan_from_root(&root, &config).unwrap();
+
+    assert_eq!(projects.len(), 2);
+    assert!(projects.iter().any(|p| p.ends_with("foo")));
+    assert!(projects.iter().any(|p| p.ends_with("bar")));
+}
+
+#[test]
+fn should_not_descend_into_hidden_dirs() {
+    let (_dir, root) = make_scan_root();
+    fs::create_dir_all(root.join(".hidden/repo/.git")).unwrap();
+
+    let config = make_config(5);
+    let (projects, _) = scan_from_root(&root, &config).unwrap();
+
+    assert!(projects.is_empty());
+}
+
+#[test]
+fn should_respect_max_depth() {
+    let (_dir, root) = make_scan_root();
+    // Shallow: project/.git at depth 2 from root — found with max_depth=2
+    fs::create_dir_all(root.join("project/.git")).unwrap();
+    // Deep: nested/deep/project/.git at depth 4 — excluded with max_depth=2
+    fs::create_dir_all(root.join("nested/deep/project/.git")).unwrap();
+
+    let config = make_config(2);
+    let (projects, _) = scan_from_root(&root, &config).unwrap();
+
+    assert_eq!(projects.len(), 1);
+    assert!(projects[0].ends_with("project"));
+}

tests/session_config.rs

@@ -0,0 +1,26 @@
+use std::fs;
+use tempfile::tempdir;
+use tmuxido::session::SessionConfig;
+
+#[test]
+fn should_load_project_session_config() {
+    let dir = tempdir().unwrap();
+    let config_content = r#"
+        [[windows]]
+        name = "editor"
+        panes = ["nvim ."]
+    "#;
+    fs::write(dir.path().join(".tmuxido.toml"), config_content).unwrap();
+
+    let result = SessionConfig::load_from_project(dir.path()).unwrap();
+    assert!(result.is_some());
+    let config = result.unwrap();
+    assert_eq!(config.windows[0].name, "editor");
+}
+
+#[test]
+fn should_return_none_when_no_project_config() {
+    let dir = tempdir().unwrap();
+    let result = SessionConfig::load_from_project(dir.path()).unwrap();
+    assert!(result.is_none());
+}