add changelog entry and generalize tests for opt-in rules

CHANGELOG.md

@@ -43,6 +43,9 @@
   [JP Simard](https://github.com/jpsim)
   [#256](https://github.com/realm/SwiftLint/issues/256)
 
+* Add opt-in "Missing Docs" rule to detect undocumented public declarations.  
+  [JP Simard](https://github.com/jpsim)
+
 ##### Bug Fixes
 
 * AutoCorrect for TrailingNewlineRule only removes at most one line.  

Source/SwiftLintFrameworkTests/ConfigurationTests.swift

@@ -10,6 +10,8 @@ import SwiftLintFramework
 import SourceKittenFramework
 import XCTest
 
+let optInRules = masterRuleList.list.filter({ $0.1.init() is OptInRule }).map({ $0.0 })
+
 class ConfigurationTests: XCTestCase {
     func testInit() {
         XCTAssert(Configuration(dict: [:]) != nil,
@@ -36,7 +38,7 @@ class ConfigurationTests: XCTestCase {
             ["nesting", "todo"],
             "initializing Configuration with valid rules in Dictionary should succeed")
         let expectedIdentifiers = Array(masterRuleList.list.keys)
-            .filter({ !["nesting", "todo", "missing_docs"].contains($0) })
+            .filter({ !(["nesting", "todo"] + optInRules).contains($0) })
         let configuredIdentifiers = disabledConfig.rules.map {
             $0.dynamicType.description.identifier
         }
@@ -57,7 +59,7 @@ class ConfigurationTests: XCTestCase {
             [validRule],
             "initializing Configuration with valid rules in YAML string should succeed")
         let expectedIdentifiers = Array(masterRuleList.list.keys)
-            .filter({ ![validRule, "missing_docs"].contains($0) })
+            .filter({ !([validRule] + optInRules).contains($0) })
         let configuredIdentifiers = configuration.rules.map {
             $0.dynamicType.description.identifier
         }