feat(config): Add .revu.yml config file and its loader

.revu.yml

@@ -0,0 +1,12 @@
+# Revu Configuration File
+
+# Coding guidelines for code reviews
+codingGuidelines:
+  - "Test coverage: Critical code requires 100% test coverage; non-critical paths require 60% coverage."
+  - "Naming: Use semantically significant names for functions, classes, and parameters."
+  - "Comments: Add comments only for complex code; simple code should be self-explanatory."
+  - "Documentation: Public functions must have concise docstrings explaining purpose and return values."
+
+# Review settings (for future use)
+reviewSettings:
+  # Future configuration options can be added here

README.md

@@ -8,7 +8,8 @@ Revu is a GitHub App that leverages Anthropic's Claude AI to provide intelligent
 - **Intelligent Feedback**: Provides detailed explanations and suggestions for improvements
 - **Git-Aware**: Considers commit history and branch differences
 - **GitHub Integration**: Seamlessly integrates with GitHub's PR workflow
-- **Customizable**: Configurable through environment variables and templates
+- **Customizable**: Configurable through environment variables, templates, and coding guidelines
+- **Coding Guidelines**: Enforce custom coding standards through configuration.
 
 ## How It Works
 
@@ -185,11 +186,37 @@ extractLogFromRepo({
 
 ### Configuration
 
+#### Model Configuration
+
 - Model: Claude 3 Sonnet
 - Max tokens: 4096
 - Temperature: 0.7
 - Required env: `ANTHROPIC_API_KEY`
 
+#### Coding Guidelines Configuration
+
+Revu supports custom coding guidelines through a `.revu.yml` YAML configuration file in the project root:
+
+```yaml
+# .revu.yml file structure
+codingGuidelines:
+  - "Test coverage: Critical code requires 100% test coverage; non-critical paths require 60% coverage."
+  - "Naming: Use semantically significant names for functions, classes, and parameters."
+  - "Comments: Add comments only for complex code; simple code should be self-explanatory."
+  - "Documentation: Public functions must have concise docstrings explaining purpose and return values."
+
+reviewSettings:
+  # Future configuration options for review behavior
+```
+
+The configuration supports:
+
+- **Hierarchical Structure**: Organized by configuration type
+- **User Overrides**: Repository-specific `.revu.yml` files can override default settings
+- **Extensible Design**: Ready for future configuration options
+
+Guidelines are automatically included in code review comments to ensure consistent standards across your projects.
+
 ## Troubleshooting
 
 ### Common Issues

__tests__/config-handler.test.ts

@@ -0,0 +1,143 @@
+import * as fs from 'fs/promises'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import {
+  formatCodingGuidelines,
+  getDefaultConfig,
+  mergeConfigs,
+  readConfig,
+  type CodingGuidelinesConfig
+} from '../src/config-handler.ts'
+
+// Mock fs.promises
+vi.mock('fs/promises', () => ({
+  readFile: vi.fn(),
+  access: vi.fn()
+}))
+
+// Mock path
+vi.mock('path', () => ({
+  join: vi.fn((...args) => args.join('/'))
+}))
+
+describe('Config Handler', () => {
+  beforeEach(() => {
+    vi.resetAllMocks()
+  })
+
+  afterEach(() => {
+    vi.clearAllMocks()
+  })
+
+  describe('readConfig', () => {
+    it('should return default config when file does not exist', async () => {
+      // Mock fs.access to throw an error (file doesn't exist)
+      vi.mocked(fs.access).mockRejectedValueOnce(new Error('File not found'))
+
+      const config = await readConfig()
+      expect(config).toEqual(getDefaultConfig())
+    })
+
+    it('should read and parse YAML config file', async () => {
+      // Mock file content
+      const mockYamlContent = `
+codingGuidelines:
+  - "Test guideline 1"
+  - "Test guideline 2"
+reviewSettings:
+  setting1: value1
+`
+      // Mock successful file access
+      vi.mocked(fs.access).mockResolvedValueOnce(undefined)
+      // Mock file read
+      vi.mocked(fs.readFile).mockResolvedValueOnce(mockYamlContent)
+
+      const config = await readConfig()
+      expect(config.codingGuidelines).toEqual([
+        'Test guideline 1',
+        'Test guideline 2'
+      ])
+      expect(config.reviewSettings).toEqual({ setting1: 'value1' })
+    })
+
+    it('should return default config on error', async () => {
+      // Mock fs.access to succeed but fs.readFile to fail
+      vi.mocked(fs.access).mockResolvedValueOnce(undefined)
+      vi.mocked(fs.readFile).mockRejectedValueOnce(new Error('Read error'))
+
+      const config = await readConfig()
+      expect(config).toEqual(getDefaultConfig())
+    })
+  })
+
+  describe('formatCodingGuidelines', () => {
+    it('should format guidelines as numbered list', () => {
+      const config = {
+        codingGuidelines: ['Guideline 1', 'Guideline 2', 'Guideline 3'],
+        reviewSettings: {}
+      }
+
+      const formatted = formatCodingGuidelines(config)
+      expect(formatted).toBe('1. Guideline 1\n2. Guideline 2\n3. Guideline 3')
+    })
+
+    it('should handle empty guidelines array', () => {
+      const config = {
+        codingGuidelines: [],
+        reviewSettings: {}
+      }
+
+      const formatted = formatCodingGuidelines(config)
+      expect(formatted).toBe('No specific coding guidelines defined.')
+    })
+
+    it('should handle missing guidelines', () => {
+      // Create a config object without codingGuidelines
+      const config = {
+        reviewSettings: {}
+      } as CodingGuidelinesConfig
+
+      const formatted = formatCodingGuidelines(config)
+      expect(formatted).toBe('No specific coding guidelines defined.')
+    })
+  })
+
+  describe('mergeConfigs', () => {
+    it('should merge configs with user config overriding defaults', () => {
+      const defaultConfig = {
+        codingGuidelines: ['Default 1', 'Default 2'],
+        reviewSettings: {
+          setting1: 'default1',
+          setting2: 'default2'
+        }
+      }
+
+      const userConfig = {
+        codingGuidelines: ['User 1', 'User 2'],
+        reviewSettings: {
+          setting1: 'user1'
+        }
+      }
+
+      const merged = mergeConfigs(defaultConfig, userConfig)
+      expect(merged).toEqual({
+        codingGuidelines: ['User 1', 'User 2'],
+        reviewSettings: {
+          setting1: 'user1',
+          setting2: 'default2'
+        }
+      })
+    })
+
+    it('should handle null or undefined user config', () => {
+      const defaultConfig = getDefaultConfig()
+
+      expect(
+        mergeConfigs(defaultConfig, null as Partial<typeof defaultConfig>)
+      ).toEqual(defaultConfig)
+
+      expect(
+        mergeConfigs(defaultConfig, undefined as Partial<typeof defaultConfig>)
+      ).toEqual(defaultConfig)
+    })
+  })
+})

package.json

@@ -20,11 +20,13 @@
     "@anthropic-ai/sdk": "^0.40.0",
     "dotenv": "^16.4.7",
     "handlebars": "^4.7.8",
+    "js-yaml": "^4.1.0",
     "probot": "^13.4.3"
   },
   "devDependencies": {
     "@eslint/eslintrc": "^3.3.1",
     "@eslint/js": "^9.25.1",
+    "@types/js-yaml": "^4.0.9",
     "@types/node": "22.15.3",
     "@typescript-eslint/eslint-plugin": "^8.24.1",
     "@typescript-eslint/parser": "^8.24.1",

src/config-handler.ts

@@ -0,0 +1,170 @@
+import * as fs from 'fs/promises'
+import * as yaml from 'js-yaml'
+import * as path from 'path'
+
+/**
+ * Check if a file exists
+ *
+ * @param filePath - Path to the file to check
+ * @returns True if the file exists, false otherwise
+ */
+async function fileExists(filePath: string): Promise<boolean> {
+  try {
+    await fs.access(filePath)
+    return true
+  } catch {
+    return false
+  }
+}
+
+/**
+ * Interface for the coding guidelines configuration
+ */
+export interface CodingGuidelinesConfig {
+  codingGuidelines: string[]
+  reviewSettings: Record<string, unknown>
+  [key: string]: unknown // Allow for future configuration options
+}
+
+/**
+ * Default coding guidelines configuration
+ */
+const DEFAULT_CONFIG: CodingGuidelinesConfig = {
+  codingGuidelines: [
+    'Test coverage: Critical code requires 100% test coverage; non-critical paths require 60% coverage.',
+    'Naming: Use semantically significant names for functions, classes, and parameters.',
+    'Comments: Add comments only for complex code; simple code should be self-explanatory.',
+    'Documentation: Public functions must have concise docstrings explaining purpose and return values.'
+  ],
+  reviewSettings: {
+    // Future configuration options can be added here
+  }
+}
+
+/**
+ * Reads the .revu.yml configuration file from the specified path
+ *
+ * @param configPath - Path to the .revu.yml configuration file
+ * @returns The parsed configuration object
+ */
+export async function readConfig(
+  configPath = path.join(process.cwd(), '.revu.yml')
+): Promise<CodingGuidelinesConfig> {
+  try {
+    // Check if the config file exists
+    const exists = await fileExists(configPath)
+    if (!exists) {
+      console.log('No .revu.yml configuration file found, using defaults')
+      return DEFAULT_CONFIG
+    }
+
+    // Read and parse the YAML file
+    const configContent = await fs.readFile(configPath, 'utf-8')
+    const config = yaml.load(configContent) as CodingGuidelinesConfig
+
+    // Merge with default config to ensure all required fields exist
+    return mergeConfigs(DEFAULT_CONFIG, config)
+  } catch (error) {
+    console.error('Error reading .revu.yml configuration file:', error)
+    return DEFAULT_CONFIG
+  }
+}
+
+/**
+ * Gets the default configuration
+ *
+ * @returns The default configuration object
+ */
+export function getDefaultConfig(): CodingGuidelinesConfig {
+  return { ...DEFAULT_CONFIG }
+}
+
+/**
+ * Gets the coding guidelines from the configuration
+ *
+ * @param config - The configuration object
+ * @returns The coding guidelines as a formatted string
+ */
+export function formatCodingGuidelines(config: CodingGuidelinesConfig): string {
+  if (
+    !config.codingGuidelines ||
+    !Array.isArray(config.codingGuidelines) ||
+    config.codingGuidelines.length === 0
+  ) {
+    return 'No specific coding guidelines defined.'
+  }
+
+  return config.codingGuidelines
+    .map((guideline, index) => `${index + 1}. ${guideline}`)
+    .join('\n')
+}
+
+/**
+ * Merges two configuration objects, with the user config overriding the default config
+ * for any keys that exist in both.
+ *
+ * @param defaultConfig - The default configuration object
+ * @param userConfig - The user configuration object
+ * @returns The merged configuration object
+ */
+export function mergeConfigs(
+  defaultConfig: CodingGuidelinesConfig,
+  userConfig: Partial<CodingGuidelinesConfig>
+): CodingGuidelinesConfig {
+  // Start with a copy of the default config
+  const result = { ...defaultConfig }
+
+  // If userConfig is not an object or is null, return the default
+  if (!userConfig || typeof userConfig !== 'object') {
+    return result
+  }
+
+  // Iterate through the keys in the user config
+  for (const key in userConfig) {
+    const userValue = userConfig[key]
+    const defaultValue = defaultConfig[key]
+
+    // If both values are objects, recursively merge them
+    if (
+      userValue &&
+      typeof userValue === 'object' &&
+      !Array.isArray(userValue) &&
+      defaultValue &&
+      typeof defaultValue === 'object' &&
+      !Array.isArray(defaultValue)
+    ) {
+      // Use type assertion to handle nested objects
+      result[key] = mergeConfigs(
+        defaultValue as CodingGuidelinesConfig,
+        userValue as Partial<CodingGuidelinesConfig>
+      )
+    } else {
+      // Otherwise, use the user value
+      result[key] = userValue
+    }
+  }
+
+  return result
+}
+
+/**
+ * Gets the coding guidelines from the configuration
+ *
+ * @param repoPath - Optional path to the repository
+ * @returns The coding guidelines as a formatted string
+ */
+export async function getCodingGuidelines(repoPath?: string): Promise<string> {
+  let configPath = path.join(process.cwd(), '.revu.yml')
+
+  // If a repository path is provided, check for a .revu.yml file there
+  if (repoPath) {
+    const repoConfigPath = path.join(repoPath, '.revu.yml')
+    const exists = await fileExists(repoConfigPath)
+    if (exists) {
+      configPath = repoConfigPath
+    }
+  }
+
+  const config = await readConfig(configPath)
+  return formatCodingGuidelines(config)
+}