feat(config): more sophisticated param validation

spec/config_spec.lua

@@ -119,6 +119,111 @@ describe('cp.config', function()
         end)
       end)
     end)
+
+    describe('auto-configuration', function()
+      it('sets default extensions for cpp and python', function()
+        local user_config = {
+          contests = {
+            test = {
+              cpp = { compile = { 'g++' } },
+              python = { test = { 'python3' } },
+            },
+          },
+        }
+
+        local result = config.setup(user_config)
+
+        assert.equals('cpp', result.contests.test.cpp.extension)
+        assert.equals('py', result.contests.test.python.extension)
+      end)
+
+      it('sets default_language to cpp when available', function()
+        local user_config = {
+          contests = {
+            test = {
+              cpp = { compile = { 'g++' } },
+              python = { test = { 'python3' } },
+            },
+          },
+        }
+
+        local result = config.setup(user_config)
+
+        assert.equals('cpp', result.contests.test.default_language)
+      end)
+
+      it('sets default_language to first available when cpp not present', function()
+        local user_config = {
+          contests = {
+            test = {
+              python = { test = { 'python3' } },
+              rust = { compile = { 'rustc' } },
+            },
+          },
+        }
+
+        local result = config.setup(user_config)
+
+        assert.equals('python', result.contests.test.default_language)
+      end)
+
+      it('preserves explicit default_language', function()
+        local user_config = {
+          contests = {
+            test = {
+              cpp = { compile = { 'g++' } },
+              python = { test = { 'python3' } },
+              default_language = 'python',
+            },
+          },
+        }
+
+        local result = config.setup(user_config)
+
+        assert.equals('python', result.contests.test.default_language)
+      end)
+
+      it('errors when no language configurations exist', function()
+        local invalid_config = {
+          contests = {
+            test = {},
+          },
+        }
+
+        assert.has_error(function()
+          config.setup(invalid_config)
+        end, 'No language configurations found for test')
+      end)
+
+      it('validates language names against canonical_filetypes', function()
+        local invalid_config = {
+          contests = {
+            test = {
+              invalid_lang = { compile = { 'gcc' } },
+            },
+          },
+        }
+
+        assert.has_error(function()
+          config.setup(invalid_config)
+        end, "Invalid language 'invalid_lang'")
+      end)
+
+      it('validates default_language value', function()
+        local invalid_config = {
+          contests = {
+            test = {
+              cpp = { compile = { 'g++' } },
+              default_language = 'xd',
+            },
+          },
+        }
+
+        assert.has_error(function()
+          config.setup(invalid_config)
+        end, "Invalid default_language 'xd'")
+      end)
+    end)
   end)
 
   describe('default_filename', function()

spec/execute_spec.lua

@@ -186,18 +186,15 @@ describe('cp.execute', function()
         }
       end
 
-      -- Test the internal execute_command function indirectly
       local language_config = {
         run = { '{binary_file}' },
       }
 
-      -- This would be called by a higher-level function that uses execute_command
       execute.compile_generic(language_config, { binary_file = './test.run' })
     end)
 
     it('handles command execution', function()
       vim.system = function(_, opts)
-        -- Compilation doesn't set timeout, only text=true
         if opts then
           assert.equals(true, opts.text)
         end
@@ -259,8 +256,6 @@ describe('cp.execute', function()
 
   describe('directory creation', function()
     it('creates build and io directories', function()
-      -- This tests the ensure_directories function indirectly
-      -- since it's called by other functions
       local language_config = {
         compile = { 'mkdir', '-p', 'build', 'io' },
       }
@@ -276,15 +271,10 @@ describe('cp.execute', function()
 
   describe('language detection', function()
     it('detects cpp from extension', function()
-      -- This tests get_language_from_file indirectly
-
-      -- Mock the file extension detection
       vim.fn.fnamemodify = function()
         return 'cpp'
       end
 
-      -- The actual function is local, but we can test it indirectly
-      -- through functions that use it
       assert.has_no_errors(function()
         execute.compile_generic({}, {})
       end)

spec/scraper_spec.lua

@@ -111,7 +111,6 @@ describe('cp.scrape', function()
         stored_data = { platform = platform, contest_id = contest_id, problems = problems }
       end
 
-      -- Reload the scraper module to pick up the updated mock
       package.loaded['cp.scrape'] = nil
       scrape = require('cp.scrape')