[doclint] Start linting method arguments

This patch introduces a general Documentation.diff method, which
produces a diff of two documentations.

With this, the patch teaches documentation linter to lint method arguments.

References #14.

docs/api.md

@@ -14,8 +14,8 @@
   * [page.addScriptTag(url)](#pageaddscripttagurl)
   * [page.click()](#pageclick)
   * [page.close()](#pageclose)
-  * [page.evaluate(fun, args)](#pageevaluatefun-args)
+  * [page.evaluate(fun, ...args)](#pageevaluatefun-args)
-  * [page.evaluateOnInitialized(fun, args)](#pageevaluateoninitializedfun-args)
+  * [page.evaluateOnInitialized(fun, ...args)](#pageevaluateoninitializedfun-args)
   * [page.focus()](#pagefocus)
   * [page.frames()](#pageframes)
   * [page.httpHeaders()](#pagehttpheaders)
@@ -44,7 +44,7 @@
   * [dialog.message()](#dialogmessage)
 - [class: Frame](#class-frame)
   * [frame.childFrames()](#framechildframes)
-  * [frame.evaluate(fun, args)](#frameevaluatefun-args)
+  * [frame.evaluate(fun, ...args)](#frameevaluatefun-args)
   * [frame.isDetached()](#frameisdetached)
   * [frame.isMainFrame()](#frameismainframe)
   * [frame.name()](#framename)
@@ -133,16 +133,16 @@ Pages could be closed by `page.close()` method.
 
 - returns: <[Promise]> Returns promise which resolves when page gets closed.
 
-#### page.evaluate(fun, args)
+#### page.evaluate(fun, ...args)
 
 - `fun` <[function]> Function to be evaluated in browser context
-- `args` <[Array]<[string]>> Arguments to pass to  `fun`
+- `...args` <...[string]> Arguments to pass to  `fun`
 - returns: <[Promise]<[Object]>> Promise which resolves to function return value
 
-#### page.evaluateOnInitialized(fun, args)
+#### page.evaluateOnInitialized(fun, ...args)
 
 - `fun` <[function]> Function to be evaluated in browser context
-- `args` <[Array]<[string]>> Arguments to pass to  `fun`
+- `...args` <...[string]> Arguments to pass to `fun`
 - returns: <[Promise]<[Object]>> Promise which resolves to function
 
 #### page.focus()
@@ -156,7 +156,7 @@ Pages could be closed by `page.close()` method.
 
 #### page.injectFile(filePath)
 
-- `url` <[string]> Path to the javascript file to be injected into page.
+- `filePath` <[string]> Path to the javascript file to be injected into page.
 - returns: <[Promise]> Promise which resolves when file gets successfully evaluated in page.
 
 #### page.mainFrame()
@@ -222,7 +222,7 @@ The `page.navigate` will throw an error if:
 
 #### page.setInPageCallback(name, callback)
 
-- `url` <[string]> Name of the callback to be assigned on window object
+- `name` <[string]> Name of the callback to be assigned on window object
 - `callback` <[function]> Callback function which will be called in node.js
 - returns: <[Promise]> Promise which resolves when callback is successfully initialized
 
@@ -267,6 +267,12 @@ The `page.navigate` will throw an error if:
 
 #### page.waitFor(selector)
 
+- `selector` <[string]> A query selector to wait for on the page.
+
+Wait for the `selector` to appear in page. If at the moment of calling
+the method the `selector` already exists, the method will return
+immediately.
+
 Shortcut for [page.mainFrame().waitFor(selector)](#framewaitforselector).
 
 ### class: Dialog
@@ -276,10 +282,10 @@ Shortcut for [page.mainFrame().waitFor(selector)](#framewaitforselector).
 
 ### class: Frame
 #### frame.childFrames()
-#### frame.evaluate(fun, args)
+#### frame.evaluate(fun, ...args)
 
 - `fun` <[function]> Function to be evaluated in browser context
-- `args` <[Array]<[string]>> Arguments to pass to  `fun`
+- `...args` <[Array]<[string]>> Arguments to pass to  `fun`
 - returns: <[Promise]<[Object]>> Promise which resolves to function return value
 
 #### frame.isDetached()

lib/Page.js

@@ -583,13 +583,13 @@ class Page extends EventEmitter {
 
   /**
    * @param {string} selector
-   * @param {!Array<string>} files
+   * @param {!Array<string>} filePaths
    * @return {!Promise}
    */
-  async uploadFile(selector, ...files) {
+  async uploadFile(selector, ...filePaths) {
     try {
       const nodeId = await this._querySelector(selector);
-      await this._client.send('DOM.setFileInputFiles', { nodeId, files });
+      await this._client.send('DOM.setFileInputFiles', { nodeId, files: filePaths });
     } finally {
       await this._client.send('DOM.disable');
     }

test/doclint/Documentation.js

@@ -1,4 +1,56 @@
-let Documentation = {};
+class Documentation {
+  /**
+   * @param {!Array<!Documentation.Class>} clasesArray
+   */
+  constructor(classesArray) {
+    this.classesArray = classesArray;
+    this.classes = new Map();
+    for (let cls of classesArray)
+      this.classes.set(cls.name, cls);
+  }
+
+  /**
+   * @param {!Documentation} actual
+   * @param {!Documentation} expected
+   */
+  static diff(actual, expected) {
+    const result = {};
+    // Diff classes.
+    const actualClasses = Array.from(actual.classes.keys()).sort();
+    const expectedClasses = Array.from(expected.classes.keys()).sort();
+    let classesDiff = diff(actualClasses, expectedClasses);
+    result.extraClasses = classesDiff.extra;
+    result.missingClasses = classesDiff.missing;
+
+    result.extraMethods = [];
+    result.missingMethods = [];
+    result.badArguments = [];
+    for (let className of classesDiff.equal) {
+      const actualClass = actual.classes.get(className);
+      const expectedClass = expected.classes.get(className);
+      const actualMethods = Array.from(actualClass.methods.keys()).sort();
+      const expectedMethods = Array.from(expectedClass.methods.keys()).sort();
+      const methodDiff = diff(actualMethods, expectedMethods);
+      result.extraMethods.push(...(methodDiff.extra.map(methodName => className + '.' + methodName)));
+      result.missingMethods.push(...(methodDiff.missing.map(methodName => className + '.' + methodName)));
+      for (let methodName of methodDiff.equal) {
+        const actualMethod = actualClass.methods.get(methodName);
+        const expectedMethod = expectedClass.methods.get(methodName);
+        const actualArgs = actualMethod.args.map(arg => arg.name);
+        const expectedArgs = expectedMethod.args.map(arg => arg.name);
+        const argDiff = diff(actualArgs, expectedArgs);
+        if (argDiff.extra.length || argDiff.missing.diff) {
+          result.badArguments.push({
+            method: `${className}.${methodName}`,
+            missingArgs: argDiff.missing,
+            extraArgs: argDiff.extra
+          });
+        }
+      }
+    }
+    return result;
+  }
+}
 
 Documentation.Class = class {
   /**
@@ -15,6 +67,17 @@ Documentation.Class = class {
 };
 
 Documentation.Method = class {
+  /**
+   * @param {string} name
+   * @param {!Array<!Documentation.Argument>} args
+   */
+  constructor(name, args) {
+    this.name = name;
+    this.args = args;
+  }
+};
+
+Documentation.Argument = class {
   /**
    * @param {string} name
    */
@@ -23,4 +86,78 @@ Documentation.Method = class {
   }
 };
 
+/**
+ * @param {!Array<string>} actual
+ * @param {!Array<string>} expected
+ * @return {{extra: !Array<string>, missing: !Array<string>, equal: !Array<string>}}
+ */
+function diff(actual, expected) {
+  const N = actual.length;
+  const M = expected.length;
+  if (N === 0 && M === 0)
+    return { extra: [], missing: [], equal: []};
+  if (N === 0)
+    return {extra: [], missing: expected.slice(), equal: []};
+  if (M === 0)
+    return {extra: actual.slice(), missing: [], equal: []};
+  let d = new Array(N);
+  let bt = new Array(N);
+  for (let i = 0; i < N; ++i) {
+    d[i] = new Array(M);
+    bt[i] = new Array(M);
+    for (let j = 0; j < M; ++j) {
+      const top = val(i - 1, j);
+      const left = val(i, j - 1);
+      if (top > left) {
+        d[i][j] = top;
+        bt[i][j] = 'extra';
+      } else {
+        d[i][j] = left;
+        bt[i][j] = 'missing';
+      }
+      let diag = val(i - 1, j - 1);
+      if (actual[i] === expected[j] && d[i][j] < diag + 1) {
+        d[i][j] = diag + 1;
+        bt[i][j] = 'eq';
+      }
+    }
+  }
+  // Backtrack results.
+  let i = N - 1;
+  let j = M - 1;
+  let missing = [];
+  let extra = [];
+  let equal = [];
+  while (i >= 0 && j >= 0) {
+    switch (bt[i][j]) {
+      case 'extra':
+        extra.push(actual[i]);
+        i -= 1;
+        break;
+      case 'missing':
+        missing.push(expected[j]);
+        j -= 1;
+        break;
+      case 'eq':
+        equal.push(actual[i]);
+        i -= 1;
+        j -= 1;
+        break;
+    }
+  }
+  while (i >= 0)
+    extra.push(actual[i--]);
+  while (j >= 0)
+    missing.push(expected[j--]);
+  extra.reverse();
+  missing.reverse();
+  equal.reverse();
+  return {extra, missing, equal};
+
+  function val(i, j) {
+    return i < 0 || j < 0 ? 0 : d[i][j];
+  }
+}
+
 module.exports = Documentation;
+

test/doclint/JSBuilder.js

@@ -1,3 +1,5 @@
+const fs = require('fs');
+const path = require('path');
 const esprima = require('esprima');
 const ESTreeWalker = require('../../third_party/chromium/ESTreeWalker');
 const Documentation = require('./Documentation');
@@ -22,13 +24,17 @@ class JSOutline {
 
   _onClassDeclaration(node) {
     this._flushClassIfNeeded();
-    this._currentClassName = this._getIdentifier(node.id);
+    this._currentClassName = this._extractText(node.id);
   }
 
   _onMethodDefinition(node) {
     console.assert(this._currentClassName !== null);
-    let methodName = this._getIdentifier(node.key);
+    console.assert(node.value.type === 'FunctionExpression');
-    let method = new Documentation.Method(methodName);
+    const args = [];
+    for (let param of node.value.params)
+      args.push(new Documentation.Argument(this._extractText(param)));
+    let methodName = this._extractText(node.key);
+    let method = new Documentation.Method(methodName, args);
     this._currentClassMethods.push(method);
   }
 
@@ -41,12 +47,27 @@ class JSOutline {
     this._currentClassMethods = [];
   }
 
-  _getIdentifier(node) {
+  _extractText(node) {
     if (!node)
       return null;
     let text = this._text.substring(node.range[0], node.range[1]).trim();
-    return /^[$A-Z_][0-9A-Z_$]*$/i.test(text) ? text : null;
+    return text;
   }
 }
 
-module.exports = JSOutline;
+/**
+ * @param {!Array<string>} dirPath
+ * @return {!Promise<!Documentation>}
+ */
+module.exports = async function(dirPath) {
+  let filePaths = fs.readdirSync(dirPath)
+      .filter(fileName => fileName.endsWith('.js'))
+      .map(fileName => path.join(dirPath, fileName));
+  let classes = [];
+  for (let filePath of filePaths) {
+    let outline = new JSOutline(fs.readFileSync(filePath, 'utf8'));
+    classes.push(...outline.classes);
+  }
+  return new Documentation(classes);
+};
+

test/doclint/MDBuilder.js

@@ -0,0 +1,126 @@
+const fs = require('fs');
+const markdownToc = require('markdown-toc');
+const path = require('path');
+const Documentation = require('./Documentation');
+const commonmark = require('commonmark');
+const Browser = require('../../lib/Browser');
+
+class MDOutline {
+  /**
+   * @param {!Browser} browser
+   * @param {string} text
+   * @return {!MDOutline}
+   */
+  static async create(browser, text) {
+    // Render markdown as HTML.
+    const reader = new commonmark.Parser();
+    const parsed = reader.parse(text);
+    const writer = new commonmark.HtmlRenderer();
+    const html = writer.render(parsed);
+
+    // Extract headings.
+    const page = await browser.newPage();
+    await page.setContent(html);
+    const classes = await page.evaluate(() => {
+      let classes = [];
+      let currentClass = {};
+      let method = {};
+      for (let element of document.body.querySelectorAll('h3, h4, h4 + ul > li')) {
+        if (element.matches('h3')) {
+          currentClass = {
+            name: element.textContent,
+            methods: [],
+          };
+          classes.push(currentClass);
+        } else if (element.matches('h4')) {
+          method = {
+            name: element.textContent,
+            args: []
+          };
+          currentClass.methods.push(method);
+        } else if (element.matches('li') && element.firstChild.matches && element.firstChild.matches('code')) {
+          method.args.push(element.firstChild.textContent);
+        }
+      }
+      return classes;
+    });
+    return new MDOutline(classes);
+  }
+
+  constructor(classes) {
+    this.classes = [];
+    this.errors = [];
+    const classHeading = /^class: (\w+)$/;
+    const constructorRegex = /^new (\w+)\((.*)\)$/;
+    const methodRegex = /^(\w+)\.(\w+)\((.*)\)$/;
+    let currentClassName = null;
+    let currentClassMethods = [];
+    for (const cls of classes) {
+      let match = cls.name.match(classHeading);
+      currentClassName = match[1];
+      for (let mdMethod of cls.methods) {
+        let className = null;
+        let methodName = null;
+        let parameters = null;
+        let title = mdMethod.name;
+        if (constructorRegex.test(title)) {
+          let match = title.match(constructorRegex);
+          className = match[1];
+          parameters = match[2];
+          methodName = 'constructor';
+        } else if (methodRegex.test(title)) {
+          let match = title.match(methodRegex);
+          className = match[1];
+          methodName = match[2];
+          parameters = match[3];
+        }
+
+        if (!currentClassName || !className || !methodName || className.toLowerCase() !== currentClassName.toLowerCase()) {
+          console.warn('failed to process header as method: ' + mdMethod.name);
+          continue;
+        }
+        parameters = parameters.trim().replace(/[\[\]]/g, '');
+        if (parameters !== mdMethod.args.join(', '))
+          this.errors.push(`Heading arguments for "${mdMethod.name}" do not match described ones, i.e. "${parameters}" != "${mdMethod.args.join(', ')}"`);
+        let args = mdMethod.args.map(arg => new Documentation.Argument(arg));
+        let method = new Documentation.Method(methodName, args);
+        currentClassMethods.push(method);
+      }
+      flushClassIfNeeded.call(this);
+    }
+
+    function flushClassIfNeeded() {
+      if (currentClassName === null)
+        return;
+      this.classes.push(new Documentation.Class(currentClassName, currentClassMethods));
+      currentClassName = null;
+      currentClassMethods = [];
+    }
+  }
+}
+
+/**
+ * @param {!Array<string>} dirPath
+ * @return {!Promise<{documentation: !Documentation, errors: !Array<string>}>}
+ */
+module.exports = async function(dirPath) {
+  let filePaths = fs.readdirSync(dirPath)
+      .filter(fileName => fileName.endsWith('.md'))
+      .map(fileName => path.join(dirPath, fileName));
+  let classes = [];
+  let errors = [];
+  const browser = new Browser({args: ['--no-sandbox']});
+  for (let filePath of filePaths) {
+    const markdownText = fs.readFileSync(filePath, 'utf8');
+    const newMarkdownText = markdownToc.insert(markdownText);
+    if (markdownText !== newMarkdownText)
+      errors.push('Markdown TOC is outdated, run `yarn generate-toc`');
+    let outline = await MDOutline.create(browser, markdownText);
+    classes.push(...outline.classes);
+    errors.push(...outline.errors);
+  }
+  await browser.close();
+  const documentation = new Documentation(classes);
+  return { documentation, errors };
+};
+

test/doclint/MDOutline.js

@@ -1,81 +0,0 @@
-const Documentation = require('./Documentation');
-const commonmark = require('commonmark');
-const Browser = require('../../lib/Browser');
-
-class MDOutline {
-  /**
-   * @return {!MDOutline}
-   */
-  static async create(text) {
-    // Render markdown as HTML.
-    const reader = new commonmark.Parser();
-    const parsed = reader.parse(text);
-    const writer = new commonmark.HtmlRenderer();
-    const html = writer.render(parsed);
-
-    // Extract headings.
-    const browser = new Browser({args: ['--no-sandbox']});
-    const page = await browser.newPage();
-    await page.setContent(html);
-    const headings = await page.evaluate(() => {
-      let headings = {};
-      let methods = [];
-      for (let header of document.body.querySelectorAll('h3,h4')) {
-        if (header.matches('h3')) {
-          methods = [];
-          headings[header.textContent] = methods;
-        } else {
-          methods.push(header.textContent);
-        }
-      }
-      return headings;
-    });
-    await browser.close();
-    return new MDOutline(headings);
-  }
-
-  constructor(headings) {
-    this.classes = [];
-    const classHeading = /^class: (\w+)$/;
-    const constructorRegex = /^new (\w+)\((.*)\)$/;
-    const methodRegex = /^(\w+)\.(\w+)\((.*)\)$/;
-    let currentClassName = null;
-    let currentClassMethods = [];
-    for (const heading of Object.keys(headings)) {
-
-      let match = heading.match(classHeading);
-      currentClassName = match[1];
-      for (const title of headings[heading]) {
-        let className = null;
-        let methodName = null;
-        if (constructorRegex.test(title)) {
-          let match = title.match(constructorRegex);
-          className = match[1];
-          methodName = 'constructor';
-        } else if (methodRegex.test(title)) {
-          let match = title.match(methodRegex);
-          className = match[1];
-          methodName = match[2];
-        }
-
-        if (!currentClassName || !className || !methodName || className.toLowerCase() !== currentClassName.toLowerCase()) {
-          console.warn('failed to process header as method: ' + heading);
-          continue;
-        }
-        let method = new Documentation.Method(methodName);
-        currentClassMethods.push(method);
-      }
-      flushClassIfNeeded.call(this);
-    }
-
-    function flushClassIfNeeded() {
-      if (currentClassName === null)
-        return;
-      this.classes.push(new Documentation.Class(currentClassName, currentClassMethods));
-      currentClassName = null;
-      currentClassMethods = [];
-    }
-  }
-}
-
-module.exports = MDOutline;

test/doclint/lint.js

@@ -1,12 +1,9 @@
-const fs = require('fs');
 const path = require('path');
-const JSOutline = require('./JSOutline');
+const jsBuilder = require('./JSBuilder');
-const MDOutline = require('./MDOutline');
+const mdBuilder = require('./MDBuilder');
 const Documentation = require('./Documentation');
-const markdownToc = require('markdown-toc');
 
 const PROJECT_DIR = path.join(__dirname, '..', '..');
-const apiMdText = fs.readFileSync(path.join(PROJECT_DIR, 'docs', 'api.md'), 'utf8');
 
 let EXCLUDE_CLASSES = new Set([
   'Connection',
@@ -30,64 +27,65 @@ let EXCLUDE_METHODS = new Set([
   'Response.constructor',
 ]);
 
-// Build up documentation from JS sources.
+/**
-let jsClassesArray = [];
+ * @param {!Documentation} jsDocumentation
-let files = fs.readdirSync(path.join(PROJECT_DIR, 'lib'));
+ * @return {!Documentation}
-for (let file of files) {
+ */
-  if (!file.endsWith('.js'))
+function filterJSDocumentation(jsDocumentation) {
-    continue;
+  // Filter classes and methods.
-  let filePath = path.join(PROJECT_DIR, 'lib', file);
+  let classes = [];
-  let outline = new JSOutline(fs.readFileSync(filePath, 'utf8'));
+  for (let cls of jsDocumentation.classesArray) {
-  // Filter out private classes and methods.
-  for (let cls of outline.classes) {
     if (EXCLUDE_CLASSES.has(cls.name))
       continue;
-    let methodsArray = cls.methodsArray.filter(method => {
+    let methods = cls.methodsArray.filter(method => {
       if (method.name.startsWith('_'))
         return false;
-      let shorthand = `${cls.name}.${method.name}`;
+      return !EXCLUDE_METHODS.has(`${cls.name}.${method.name}`);
-      return !EXCLUDE_METHODS.has(shorthand);
     });
-    jsClassesArray.push(new Documentation.Class(cls.name, methodsArray));
+    classes.push(new Documentation.Class(cls.name, methods));
   }
+  return new Documentation(classes);
 }
 
-let mdClassesArray;
+let jsDocumentation;
+let mdDocumentation;
+let mdParseErrors;
+let diff;
 
 beforeAll(SX(async function() {
-  // Build up documentation from MD sources.
+  jsDocumentation = filterJSDocumentation(await jsBuilder(path.join(PROJECT_DIR, 'lib')));
-  let mdOutline = await MDOutline.create(apiMdText);
+  let mdDoc = await mdBuilder(path.join(PROJECT_DIR, 'docs'));
-  mdClassesArray = mdOutline.classes;
+  mdDocumentation = mdDoc.documentation;
+  mdParseErrors = mdDoc.errors;
+  diff = Documentation.diff(mdDocumentation, jsDocumentation);
 }));
 
-describe('table of contents', function() {
+describe('JavaScript documentation parser', function() {
-  it('should match markdown-toc\'s output', () => {
+  it('should not contain any duplicate classes (probably error in parsing!)', () => {
-    const newApiMdText = markdownToc.insert(apiMdText);
+    let jsClasses = new Map();
-    if (apiMdText !== newApiMdText)
+    for (let jsClass of jsDocumentation.classesArray) {
-      fail('markdown TOC is outdated, run `yarn generate-toc`');
-  });
-});
-
-// Compare to codebase.
-describe('api.md', function() {
-  let mdClasses = new Map();
-  let jsClasses = new Map();
-  it('MarkDown should not contain any duplicate classes', () => {
-    for (let mdClass of mdClassesArray) {
-      if (mdClasses.has(mdClass.name))
-        fail(`Documentation has duplicate declaration of ${mdClass.name}`);
-      mdClasses.set(mdClass.name, mdClass);
-    }
-  });
-  it('JavaScript should not contain any duplicate classes (probably error in parsing!)', () => {
-    for (let jsClass of jsClassesArray) {
       if (jsClasses.has(jsClass.name))
         fail(`JavaScript has duplicate declaration of ${jsClass.name}. (This probably means that this linter has an error)`);
       jsClasses.set(jsClass.name, jsClass);
     }
   });
+});
+
+describe('Markdown Documentation', function() {
+  it('should not have any parse errors', () => {
+    for (let error of mdParseErrors)
+      fail(error);
+  });
+  it('should not contain any duplicate classes', () => {
+    let mdClasses = new Map();
+    for (let mdClass of mdDocumentation.classesArray) {
+      if (mdClasses.has(mdClass.name))
+        fail(`Documentation has duplicate declaration of class ${mdClass.name}`);
+      mdClasses.set(mdClass.name, mdClass);
+    }
+  });
   it('class constructors should be defined before other methods', () => {
-    for (let mdClass of mdClasses.values()) {
+    for (let mdClass of mdDocumentation.classesArray) {
       let constructorMethod = mdClass.methods.get('constructor');
       if (!constructorMethod)
         continue;
@@ -96,7 +94,7 @@ describe('api.md', function() {
     }
   });
   it('methods should be sorted alphabetically', () => {
-    for (let mdClass of mdClasses.values()) {
+    for (let mdClass of mdDocumentation.classesArray) {
       for (let i = 0; i < mdClass.methodsArray.length - 1; ++i) {
         // Constructor should always go first.
         if (mdClass.methodsArray[i].name === 'constructor')
@@ -109,37 +107,29 @@ describe('api.md', function() {
     }
   });
   it('should not contain any non-existing class', () => {
-    for (let mdClass of mdClasses.values()) {
+    for (let className of diff.extraClasses)
-      if (!jsClasses.has(mdClass.name))
+      fail(`Documentation describes non-existing class ${className}`);
-        fail(`Documentation describes non-existing class ${mdClass.name}`);
-    }
   });
   it('should describe all existing classes', () => {
-    for (let jsClass of jsClasses.values()) {
+    for (let className of diff.missingClasses)
-      if (!mdClasses.has(jsClass.name))
+      fail(`Documentation lacks description of class ${className}`);
-        fail(`Documentation lacks description of class ${jsClass.name}`);
-    }
   });
   it('should not contain any non-existing methods', () => {
-    for (let mdClass of mdClasses.values()) {
+    for (let methodName of diff.extraMethods)
-      let jsClass = jsClasses.get(mdClass.name);
+      fail(`Documentation describes non-existing method: ${methodName}`);
-      if (!jsClass)
-        continue;
-      for (let method of mdClass.methods.values()) {
-        if (!jsClass.methods.has(method.name))
-          fail(`Documentation describes non-existing method: ${jsClass.name}.${method.name}()`);
-      }
-    }
   });
   it('should describe all existing methods', () => {
-    for (let jsClass of jsClasses.values()) {
+    for (let methodName of diff.missingMethods)
-      let mdClass = mdClasses.get(jsClass.name);
+      fail(`Documentation lacks method ${methodName}`);
-      if (!mdClass)
+  });
-        continue;
+  it('should describe all arguments propertly', () => {
-      for (let method of jsClass.methods.values()) {
+    for (let badArgument of diff.badArguments) {
-        if (!mdClass.methods.has(method.name))
+      let text = [`Method ${badArgument.method} fails to describe its parameters:`];
-          fail(`Documentation lacks ${jsClass.name}.${method.name}()`);
+      for (let missing of badArgument.missingArgs)
-      }
+        text.push(`- Missing description for "${missing}"`);
+      for (let extra of badArgument.extraArgs)
+        text.push(`- Described non-existing parameter "${extra}"`);
+      fail(text.join('\n'));
     }
   });
 });