Add initial project structure and core functionality for ArchDoc

- Created `.gitignore` files for various directories to exclude unnecessary files.
- Added `PLAN.md` to outline the project goals and architecture documentation generation.
- Implemented the `archdoc-cli` with a command-line interface for initializing and generating documentation.
- Developed the `archdoc-core` library for analyzing Python projects and generating architecture documentation.
- Included caching mechanisms to optimize repeated analysis.
- Established a comprehensive test suite to ensure functionality and error handling.
- Updated `README.md` to provide an overview and installation instructions for ArchDoc.

archdoc-core/tests/error_handling.rs

@@ -0,0 +1,83 @@
+//! Error handling tests for ArchDoc
+//!
+//! These tests verify that ArchDoc properly handles various error conditions
+//! and edge cases.
+
+use std::path::Path;
+use std::fs;
+use tempfile::TempDir;
+use archdoc_core::{Config, scanner::FileScanner, python_analyzer::PythonAnalyzer};
+
+#[test]
+fn test_scanner_nonexistent_directory() {
+    let config = Config::default();
+    let scanner = FileScanner::new(config);
+    
+    // Try to scan a nonexistent directory
+    let result = scanner.scan_python_files(Path::new("/nonexistent/directory"));
+    assert!(result.is_err());
+    
+    // Check that we get an IO error
+    match result.unwrap_err() {
+        archdoc_core::errors::ArchDocError::Io(_) => {},
+        _ => panic!("Expected IO error"),
+    }
+}
+
+#[test]
+fn test_scanner_file_instead_of_directory() {
+    let config = Config::default();
+    let scanner = FileScanner::new(config);
+    
+    // Create a temporary file
+    let temp_dir = TempDir::new().expect("Failed to create temp dir");
+    let temp_file = temp_dir.path().join("test.txt");
+    fs::write(&temp_file, "test content").expect("Failed to write test file");
+    
+    // Try to scan a file instead of a directory
+    let result = scanner.scan_python_files(&temp_file);
+    assert!(result.is_err());
+    
+    // Check that we get an IO error
+    match result.unwrap_err() {
+        archdoc_core::errors::ArchDocError::Io(_) => {},
+        _ => panic!("Expected IO error"),
+    }
+}
+
+#[test]
+fn test_analyzer_nonexistent_file() {
+    let config = Config::default();
+    let analyzer = PythonAnalyzer::new(config);
+    
+    // Try to parse a nonexistent file
+    let result = analyzer.parse_module(Path::new("/nonexistent/file.py"));
+    assert!(result.is_err());
+    
+    // Check that we get an IO error
+    match result.unwrap_err() {
+        archdoc_core::errors::ArchDocError::Io(_) => {},
+        _ => panic!("Expected IO error"),
+    }
+}
+
+#[test]
+fn test_analyzer_invalid_python_syntax() {
+    let config = Config::default();
+    let analyzer = PythonAnalyzer::new(config);
+    
+    // Create a temporary file with invalid Python syntax
+    let temp_dir = TempDir::new().expect("Failed to create temp dir");
+    let temp_file = temp_dir.path().join("invalid.py");
+    fs::write(&temp_file, "invalid python syntax @@#$%").expect("Failed to write test file");
+    
+    // Try to parse the file
+    let result = analyzer.parse_module(&temp_file);
+    assert!(result.is_err());
+    
+    // Check that we get a parse error
+    match result.unwrap_err() {
+        archdoc_core::errors::ArchDocError::ParseError { .. } => {},
+        _ => panic!("Expected parse error"),
+    }
+}