diff --git a/cache_spec.lua b/cache_spec.lua
new file mode 100644
index 0000000..ce8ad5c
--- /dev/null
+++ b/cache_spec.lua
@@ -0,0 +1,55 @@
+-- Unit tests for caching system
+describe('cp.cache', function()
+  local cache
+  local temp_dir
+
+  before_each(function()
+    cache = require('cp.cache')
+    temp_dir = vim.fn.tempname()
+    vim.fn.mkdir(temp_dir, 'p')
+    -- Mock cache directory
+  end)
+
+  after_each(function()
+    -- Clean up temp files
+    vim.fn.delete(temp_dir, 'rf')
+  end)
+
+  describe('contest metadata caching', function()
+    it('stores contest metadata correctly', function()
+      -- Test storing contest data
+    end)
+
+    it('retrieves cached contest metadata', function()
+      -- Test retrieving contest data
+    end)
+
+    it('handles missing cache files gracefully', function()
+      -- Test missing cache behavior
+    end)
+  end)
+
+  describe('test case caching', function()
+    it('stores test cases for problems', function()
+      -- Test test case storage
+    end)
+
+    it('retrieves cached test cases', function()
+      -- Test test case retrieval
+    end)
+
+    it('handles cache invalidation', function()
+      -- Test cache expiry/invalidation
+    end)
+  end)
+
+  describe('cache persistence', function()
+    it('persists cache across sessions', function()
+      -- Test cache file persistence
+    end)
+
+    it('handles corrupted cache files', function()
+      -- Test corrupted cache recovery
+    end)
+  end)
+end)
diff --git a/command_parsing_spec.lua b/command_parsing_spec.lua
new file mode 100644
index 0000000..0abef2b
--- /dev/null
+++ b/command_parsing_spec.lua
@@ -0,0 +1,79 @@
+-- Unit tests for command parsing and validation
+describe('cp command parsing', function()
+  local cp
+
+  before_each(function()
+    cp = require('cp')
+    cp.setup()
+  end)
+
+  describe('platform setup commands', function()
+    it('parses :CP codeforces correctly', function()
+      -- Test platform-only command parsing
+    end)
+
+    it('parses :CP codeforces 1800 correctly', function()
+      -- Test contest setup command parsing
+    end)
+
+    it('parses :CP codeforces 1800 A correctly', function()
+      -- Test full setup command parsing
+    end)
+
+    it('parses CSES format :CP cses 1068 correctly', function()
+      -- Test CSES-specific command parsing
+    end)
+  end)
+
+  describe('action commands', function()
+    it('parses :CP test correctly', function()
+      -- Test test panel command
+    end)
+
+    it('parses :CP next correctly', function()
+      -- Test navigation command
+    end)
+
+    it('parses :CP prev correctly', function()
+      -- Test navigation command
+    end)
+  end)
+
+  describe('language flags', function()
+    it('parses --lang=cpp correctly', function()
+      -- Test language flag parsing
+    end)
+
+    it('parses --debug flag correctly', function()
+      -- Test debug flag parsing
+    end)
+
+    it('combines flags correctly', function()
+      -- Test multiple flag parsing
+    end)
+  end)
+
+  describe('error handling', function()
+    it('handles invalid commands gracefully', function()
+      -- Test error messages for bad commands
+    end)
+
+    it('provides helpful error messages', function()
+      -- Test error message quality
+    end)
+  end)
+
+  describe('command completion', function()
+    it('completes platform names', function()
+      -- Test tab completion for platforms
+    end)
+
+    it('completes problem IDs from cached contest', function()
+      -- Test problem ID completion
+    end)
+
+    it('completes action names', function()
+      -- Test action completion
+    end)
+  end)
+end)
diff --git a/config_spec.lua b/config_spec.lua
new file mode 100644
index 0000000..ae1c46a
--- /dev/null
+++ b/config_spec.lua
@@ -0,0 +1,46 @@
+-- Unit tests for configuration management
+describe('cp.config', function()
+  local config
+
+  before_each(function()
+    config = require('cp.config')
+  end)
+
+  describe('setup', function()
+    it('returns default config when no user config provided', function()
+      -- Test default configuration values
+    end)
+
+    it('merges user config with defaults', function()
+      -- Test config merging behavior
+    end)
+
+    it('validates contest configurations', function()
+      -- Test contest config validation
+    end)
+
+    it('handles invalid config gracefully', function()
+      -- Test error handling for bad configs
+    end)
+  end)
+
+  describe('platform validation', function()
+    it('accepts valid platforms', function()
+      -- Test platform validation
+    end)
+
+    it('rejects invalid platforms', function()
+      -- Test platform rejection
+    end)
+  end)
+
+  describe('language configurations', function()
+    it('provides correct file extensions for languages', function()
+      -- Test language -> extension mappings
+    end)
+
+    it('provides correct compile commands', function()
+      -- Test compile command generation
+    end)
+  end)
+end)
diff --git a/execute_spec.lua b/execute_spec.lua
new file mode 100644
index 0000000..e48447f
--- /dev/null
+++ b/execute_spec.lua
@@ -0,0 +1,108 @@
+-- Unit tests for code compilation and execution
+describe('cp.execute', function()
+  local execute
+  local temp_dir
+  local test_files = {}
+
+  before_each(function()
+    execute = require('cp.execute')
+    temp_dir = vim.fn.tempname()
+    vim.fn.mkdir(temp_dir, 'p')
+    vim.api.nvim_set_current_dir(temp_dir)
+
+    -- Create sample source files for testing
+    test_files.cpp = temp_dir .. '/test.cpp'
+    test_files.python = temp_dir .. '/test.py'
+    test_files.rust = temp_dir .. '/test.rs'
+
+    -- Write simple test programs
+    vim.fn.writefile({
+      '#include <iostream>',
+      'int main() { std::cout << "Hello" << std::endl; return 0; }',
+    }, test_files.cpp)
+
+    vim.fn.writefile({
+      'print("Hello")',
+    }, test_files.python)
+  end)
+
+  after_each(function()
+    vim.fn.delete(temp_dir, 'rf')
+  end)
+
+  describe('compilation', function()
+    it('compiles C++ code successfully', function()
+      -- Test C++ compilation
+    end)
+
+    it('compiles Rust code successfully', function()
+      -- Test Rust compilation
+    end)
+
+    it('handles compilation errors', function()
+      -- Test error handling for bad code
+    end)
+
+    it('applies optimization flags correctly', function()
+      -- Test optimization settings
+    end)
+
+    it('handles debug flag correctly', function()
+      -- Test debug compilation
+    end)
+  end)
+
+  describe('execution', function()
+    it('runs compiled programs', function()
+      -- Test program execution
+    end)
+
+    it('handles runtime errors', function()
+      -- Test runtime error handling
+    end)
+
+    it('enforces time limits', function()
+      -- Test timeout handling
+    end)
+
+    it('captures output correctly', function()
+      -- Test stdout/stderr capture
+    end)
+
+    it('handles large inputs/outputs', function()
+      -- Test large data handling
+    end)
+  end)
+
+  describe('test case execution', function()
+    it('runs single test case', function()
+      -- Test individual test case execution
+    end)
+
+    it('runs multiple test cases', function()
+      -- Test batch execution
+    end)
+
+    it('compares outputs correctly', function()
+      -- Test output comparison logic
+    end)
+
+    it('handles edge cases in output comparison', function()
+      -- Test whitespace, newlines, etc.
+    end)
+  end)
+
+  describe('platform-specific execution', function()
+    it('works on Linux', function()
+      -- Test Linux-specific behavior
+    end)
+
+    it('works on macOS', function()
+      -- Test macOS-specific behavior
+    end)
+
+    it('works on Windows', function()
+      -- Test Windows-specific behavior
+    end)
+  end)
+end)
diff --git a/health_spec.lua b/health_spec.lua
new file mode 100644
index 0000000..8f43778
--- /dev/null
+++ b/health_spec.lua
@@ -0,0 +1,54 @@
+-- Unit tests for health check functionality
+describe('cp.health', function()
+  local health
+
+  before_each(function()
+    health = require('cp.health')
+  end)
+
+  describe('system checks', function()
+    it('detects Neovim version correctly', function()
+      -- Test Neovim version detection
+    end)
+
+    it('detects available compilers', function()
+      -- Test C++, Rust, etc. compiler detection
+    end)
+
+    it('detects Python installation', function()
+      -- Test Python availability
+    end)
+
+    it('checks for required external tools', function()
+      -- Test curl, wget, etc. availability
+    end)
+  end)
+
+  describe('configuration validation', function()
+    it('validates contest configurations', function()
+      -- Test config validation
+    end)
+
+    it('checks directory permissions', function()
+      -- Test write permissions for directories
+    end)
+
+    it('validates language configurations', function()
+      -- Test language setup validation
+    end)
+  end)
+
+  describe('health report generation', function()
+    it('generates comprehensive health report', function()
+      -- Test :checkhealth cp output
+    end)
+
+    it('provides actionable recommendations', function()
+      -- Test that health check gives useful advice
+    end)
+
+    it('handles partial functionality gracefully', function()
+      -- Test when some features are unavailable
+    end)
+  end)
+end)
diff --git a/integration_spec.lua b/integration_spec.lua
new file mode 100644
index 0000000..8570d2f
--- /dev/null
+++ b/integration_spec.lua
@@ -0,0 +1,114 @@
+-- Integration tests for complete workflows
+describe('cp.nvim integration', function()
+  local cp
+  local temp_dir
+
+  before_each(function()
+    cp = require('cp')
+    temp_dir = vim.fn.tempname()
+    vim.fn.mkdir(temp_dir, 'p')
+    vim.api.nvim_set_current_dir(temp_dir)
+
+    -- Set up with minimal config
+    cp.setup({
+      scrapers = {}, -- Disable scraping for integration tests
+      contests = {
+        codeforces = {
+          dir = temp_dir,
+          url = 'mock://codeforces.com',
+          languages = {
+            cpp = { extension = 'cpp', compile = 'g++ -o %s %s' },
+          },
+        },
+      },
+    })
+  end)
+
+  after_each(function()
+    vim.fn.delete(temp_dir, 'rf')
+    vim.cmd('silent! %bwipeout!')
+  end)
+
+  describe('complete problem setup workflow', function()
+    it('handles :CP codeforces 1800 A workflow', function()
+      -- Test complete setup from command to file creation
+      -- 1. Parse command
+      -- 2. Set up directory structure
+      -- 3. Create source file
+      -- 4. Apply template
+      -- 5. Switch to buffer
+    end)
+
+    it('handles CSES workflow', function()
+      -- Test CSES-specific complete workflow
+    end)
+
+    it('handles language switching', function()
+      -- Test switching languages for same problem
+    end)
+  end)
+
+  describe('problem navigation workflow', function()
+    it('navigates between problems in contest', function()
+      -- Test :CP next/:CP prev workflow
+      -- Requires cached contest metadata
+    end)
+
+    it('maintains state across navigation', function()
+      -- Test that work isn't lost when switching problems
+    end)
+  end)
+
+  describe('test panel workflow', function()
+    it('handles complete testing workflow', function()
+      -- 1. Set up problem
+      -- 2. Write solution
+      -- 3. Open test panel (:CP test)
+      -- 4. Compile and run tests
+      -- 5. View results
+      -- 6. Close panel
+    end)
+
+    it('handles debug workflow', function()
+      -- Test :CP test --debug workflow
+    end)
+  end)
+
+  describe('file system integration', function()
+    it('maintains proper directory structure', function()
+      -- Test that files are organized correctly
+    end)
+
+    it('handles existing files appropriately', function()
+      -- Test behavior when problem already exists
+    end)
+
+    it('cleans up temporary files', function()
+      -- Test cleanup of build artifacts
+    end)
+  end)
+
+  describe('error recovery', function()
+    it('recovers from network failures gracefully', function()
+      -- Test behavior when scraping fails
+    end)
+
+    it('recovers from compilation failures', function()
+      -- Test error handling in compilation
+    end)
+
+    it('handles corrupted cache gracefully', function()
+      -- Test cache corruption recovery
+    end)
+  end)
+
+  describe('multi-session behavior', function()
+    it('persists state across Neovim restarts', function()
+      -- Test that contest/problem state persists
+    end)
+
+    it('handles concurrent usage', function()
+      -- Test multiple Neovim instances
+    end)
+  end)
+end)
diff --git a/plugin/cp.lua b/plugin/cp.lua
index 7a21718..2bf4707 100644
--- a/plugin/cp.lua
+++ b/plugin/cp.lua
@@ -3,10 +3,6 @@ if vim.g.loaded_cp then
 end
 vim.g.loaded_cp = 1
 
-local constants = require('cp.constants')
-local platforms = constants.PLATFORMS
-local actions = constants.ACTIONS
-
 vim.api.nvim_create_user_command('CP', function(opts)
   local cp = require('cp')
   cp.handle_command(opts)
@@ -14,6 +10,10 @@ end, {
   nargs = '*',
   desc = 'Competitive programming helper',
   complete = function(ArgLead, CmdLine, _)
+    local constants = require('cp.constants')
+    local platforms = constants.PLATFORMS
+    local actions = constants.ACTIONS
+
     local args = vim.split(vim.trim(CmdLine), '%s+')
     local num_args = #args
     if CmdLine:sub(-1) == ' ' then
diff --git a/problem_spec.lua b/problem_spec.lua
new file mode 100644
index 0000000..c895be9
--- /dev/null
+++ b/problem_spec.lua
@@ -0,0 +1,81 @@
+-- Unit tests for problem context and file management
+describe('cp.problem', function()
+  local problem
+  local temp_dir
+
+  before_each(function()
+    problem = require('cp.problem')
+    temp_dir = vim.fn.tempname()
+    vim.fn.mkdir(temp_dir, 'p')
+    -- Change to temp directory for testing
+    vim.api.nvim_set_current_dir(temp_dir)
+  end)
+
+  after_each(function()
+    vim.fn.delete(temp_dir, 'rf')
+  end)
+
+  describe('context creation', function()
+    it('creates context for Codeforces problems', function()
+      -- Test context creation with proper paths
+    end)
+
+    it('creates context for CSES problems', function()
+      -- Test CSES-specific context
+    end)
+
+    it('generates correct file paths', function()
+      -- Test source file path generation
+    end)
+
+    it('generates correct build paths', function()
+      -- Test build directory structure
+    end)
+  end)
+
+  describe('template handling', function()
+    it('applies language templates correctly', function()
+      -- Test template application
+    end)
+
+    it('handles custom templates', function()
+      -- Test user-defined templates
+    end)
+
+    it('supports snippet integration', function()
+      -- Test LuaSnip integration
+    end)
+  end)
+
+  describe('file operations', function()
+    it('creates directory structure', function()
+      -- Test directory creation (build/, io/)
+    end)
+
+    it('handles existing files gracefully', function()
+      -- Test behavior when files exist
+    end)
+
+    it('sets up input/output files', function()
+      -- Test I/O file creation
+    end)
+  end)
+
+  describe('language support', function()
+    it('supports C++ compilation', function()
+      -- Test C++ setup and compilation
+    end)
+
+    it('supports Python execution', function()
+      -- Test Python setup
+    end)
+
+    it('supports Rust compilation', function()
+      -- Test Rust setup
+    end)
+
+    it('supports custom language configurations', function()
+      -- Test user-defined language support
+    end)
+  end)
+end)
diff --git a/scraper_spec.lua b/scraper_spec.lua
new file mode 100644
index 0000000..679b4f9
--- /dev/null
+++ b/scraper_spec.lua
@@ -0,0 +1,86 @@
+-- Unit tests for web scraping functionality
+describe('cp.scrape', function()
+  local scrape
+  local mock_responses = {}
+
+  before_each(function()
+    scrape = require('cp.scrape')
+
+    -- Mock HTTP responses for different platforms
+    mock_responses.codeforces_contest = [[
+      <div class="problems">
+        <div class="problem" data-problem-id="A">Problem A</div>
+        <div class="problem" data-problem-id="B">Problem B</div>
+      </div>
+    ]]
+
+    mock_responses.codeforces_problem = [[
+      <div class="input">Sample Input</div>
+      <div class="output">Sample Output</div>
+    ]]
+  end)
+
+  describe('contest metadata scraping', function()
+    it('scrapes Codeforces contest problems', function()
+      -- Mock HTTP request, test problem list extraction
+    end)
+
+    it('scrapes Atcoder contest problems', function()
+      -- Test Atcoder format
+    end)
+
+    it('scrapes CSES problem list', function()
+      -- Test CSES format
+    end)
+
+    it('handles network errors gracefully', function()
+      -- Test error handling for failed requests
+    end)
+
+    it('handles parsing errors gracefully', function()
+      -- Test error handling for malformed HTML
+    end)
+  end)
+
+  describe('problem scraping', function()
+    it('extracts test cases from Codeforces problems', function()
+      -- Test test case extraction
+    end)
+
+    it('handles multiple test cases correctly', function()
+      -- Test multiple sample inputs/outputs
+    end)
+
+    it('handles problems with no sample cases', function()
+      -- Test edge case handling
+    end)
+
+    it('extracts problem metadata (time limits, etc.)', function()
+      -- Test metadata extraction
+    end)
+  end)
+
+  describe('platform-specific parsing', function()
+    it('handles Codeforces HTML structure', function()
+      -- Test Codeforces-specific parsing
+    end)
+
+    it('handles Atcoder HTML structure', function()
+      -- Test Atcoder-specific parsing
+    end)
+
+    it('handles CSES HTML structure', function()
+      -- Test CSES-specific parsing
+    end)
+  end)
+
+  describe('rate limiting and caching', function()
+    it('respects rate limits', function()
+      -- Test rate limiting behavior
+    end)
+
+    it('uses cached results when appropriate', function()
+      -- Test caching integration
+    end)
+  end)
+end)
diff --git a/snippets_spec.lua b/snippets_spec.lua
new file mode 100644
index 0000000..ed81205
--- /dev/null
+++ b/snippets_spec.lua
@@ -0,0 +1,68 @@
+-- Unit tests for snippet/template functionality
+describe('cp.snippets', function()
+  local snippets
+
+  before_each(function()
+    snippets = require('cp.snippets')
+  end)
+
+  describe('template loading', function()
+    it('loads default templates correctly', function()
+      -- Test default template loading
+    end)
+
+    it('loads platform-specific templates', function()
+      -- Test Codeforces vs CSES templates
+    end)
+
+    it('loads language-specific templates', function()
+      -- Test C++ vs Python vs Rust templates
+    end)
+
+    it('handles custom user templates', function()
+      -- Test user-defined template integration
+    end)
+  end)
+
+  describe('LuaSnip integration', function()
+    it('registers snippets with LuaSnip', function()
+      -- Test snippet registration
+    end)
+
+    it('provides platform-language combinations', function()
+      -- Test snippet triggers like cp.nvim/codeforces.cpp
+    end)
+
+    it('handles missing LuaSnip gracefully', function()
+      -- Test fallback when LuaSnip not available
+    end)
+  end)
+
+  describe('template expansion', function()
+    it('expands templates with correct content', function()
+      -- Test template content expansion
+    end)
+
+    it('handles template variables', function()
+      -- Test variable substitution in templates
+    end)
+
+    it('maintains cursor positioning', function()
+      -- Test cursor placement after expansion
+    end)
+  end)
+
+  describe('template management', function()
+    it('allows template customization', function()
+      -- Test user template override
+    end)
+
+    it('supports template inheritance', function()
+      -- Test template extending/modification
+    end)
+
+    it('validates template syntax', function()
+      -- Test template validation
+    end)
+  end)
+end)
diff --git a/test_panel_spec.lua b/test_panel_spec.lua
new file mode 100644
index 0000000..41de1cc
--- /dev/null
+++ b/test_panel_spec.lua
@@ -0,0 +1,106 @@
+-- UI/buffer tests for the interactive test panel
+describe('cp test panel', function()
+  local cp
+
+  before_each(function()
+    cp = require('cp')
+    cp.setup()
+    -- Set up a clean Neovim environment
+    vim.cmd('silent! %bwipeout!')
+  end)
+
+  after_each(function()
+    -- Clean up test panel state
+    vim.cmd('silent! %bwipeout!')
+  end)
+
+  describe('panel creation', function()
+    it('creates test panel buffers', function()
+      -- Test buffer creation for tab, expected, actual views
+    end)
+
+    it('sets up correct window layout', function()
+      -- Test 3-pane layout creation
+    end)
+
+    it('applies correct buffer settings', function()
+      -- Test buffer options (buftype, filetype, etc.)
+    end)
+
+    it('sets up keymaps correctly', function()
+      -- Test navigation keymaps (Ctrl+N, Ctrl+P, q)
+    end)
+  end)
+
+  describe('test case display', function()
+    it('renders test case tabs correctly', function()
+      -- Test tab line rendering with status indicators
+    end)
+
+    it('displays input correctly', function()
+      -- Test input pane content
+    end)
+
+    it('displays expected output correctly', function()
+      -- Test expected output pane
+    end)
+
+    it('displays actual output correctly', function()
+      -- Test actual output pane
+    end)
+
+    it('shows diff when test fails', function()
+      -- Test diff mode activation
+    end)
+  end)
+
+  describe('navigation', function()
+    it('navigates to next test case', function()
+      -- Test Ctrl+N navigation
+    end)
+
+    it('navigates to previous test case', function()
+      -- Test Ctrl+P navigation
+    end)
+
+    it('wraps around at boundaries', function()
+      -- Test navigation wrapping
+    end)
+
+    it('updates display on navigation', function()
+      -- Test content updates when switching tests
+    end)
+  end)
+
+  describe('test execution integration', function()
+    it('compiles and runs tests automatically', function()
+      -- Test automatic compilation and execution
+    end)
+
+    it('updates results in real-time', function()
+      -- Test live result updates
+    end)
+
+    it('handles compilation failures', function()
+      -- Test error display when compilation fails
+    end)
+
+    it('shows execution time', function()
+      -- Test timing display
+    end)
+  end)
+
+  describe('session management', function()
+    it('saves and restores session correctly', function()
+      -- Test session save/restore when opening/closing panel
+    end)
+
+    it('handles multiple panels gracefully', function()
+      -- Test behavior with multiple test panels
+    end)
+
+    it('cleans up resources on close', function()
+      -- Test proper cleanup when closing panel
+    end)
+  end)
+end)