Add implicitly_unwrapped_optional rule

CHANGELOG.md

@@ -9,6 +9,11 @@
 
 ##### Enhancements
 
+* Add `implicitly_unwrapped_optional` rule
+  that warns when using implicitly unwrapped optional,
+  except cases when this IUO is IBOutlet.  
+  [Siarhei Fedartsou](https://github.com/SiarheiFedartsou/)
+
 * Performance improvements to `generic_type_name`,
   `redundant_nil_coalescing`, `mark`, `first_where` and
   `vertical_whitespace` rules.  
@@ -270,7 +275,7 @@
   [Marcelo Fabri](https://github.com/marcelofabri)
   [#1109](https://github.com/realm/SwiftLint/issues/1109)
 
-* Add `compiler_protocol_init` rule that flags usage of initializers 
+* Add `compiler_protocol_init` rule that flags usage of initializers
   declared in protocols used by the compiler such as `ExpressibleByArrayLiteral`
   that shouldn't be called directly. Instead, you should use a literal anywhere
   a concrete type conforming to the protocol is expected by the context.  
@@ -286,7 +291,7 @@
   [Marcelo Fabri](https://github.com/marcelofabri)
   [#51](https://github.com/realm/SwiftLint/issues/51)
 
-* Update `vertical_whitespace` rule to allow configuration of the number of 
+* Update `vertical_whitespace` rule to allow configuration of the number of
   consecutive empty lines before a violation using `max_empty_lines`.
   The default value is still 1 line.  
   [Aaron McTavish](https://github.com/aamctustwo)
@@ -312,7 +317,7 @@
   [Marcelo Fabri](https://github.com/marcelofabri)
   [#973](https://github.com/realm/SwiftLint/issues/973)
 
-* Add `unused_optional_binding` rule that will check for optional bindings 
+* Add `unused_optional_binding` rule that will check for optional bindings
   not being used.  
   [Rafael Machado](https://github.com/rakaramos/)
   [#1116](https://github.com/realm/SwiftLint/issues/1116)

Source/SwiftLintFramework/Models/MasterRuleList.swift

@@ -105,6 +105,7 @@ public let masterRuleList = RuleList(rules:
     GenericTypeNameRule.self,
     IdentifierNameRule.self,
     ImplicitGetterRule.self,
+    ImplicitlyUnwrappedOptionalRule.self,
     LargeTupleRule.self,
     LeadingWhitespaceRule.self,
     LegacyCGGeometryFunctionsRule.self,

Source/SwiftLintFramework/Rules/ImplicitlyUnwrappedOptionalRule.swift

@@ -0,0 +1,77 @@
+//
+//  ImplicitlyUnwrappedOptionalRule.swift
+//  SwiftLint
+//
+//  Created by Siarhei Fedartsou on 17/03/17.
+//  Copyright © 2016 Realm. All rights reserved.
+//
+
+import Foundation
+import SourceKittenFramework
+
+public struct ImplicitlyUnwrappedOptionalRule: ASTRule, ConfigurationProviderRule, OptInRule {
+    public var configuration = ImplicitlyUnwrappedOptionalConfiguration(mode: .allExceptIBOutlets,
+                                                                        severity: SeverityConfiguration(.warning))
+
+    public init() {}
+
+    public static let description = RuleDescription(
+        identifier: "implicitly_unwrapped_optional",
+        name: "Implicitly Unwrapped Optional",
+        description: "Implicitly unwrapped optionals should be avoided when possible.",
+        nonTriggeringExamples: [
+            "@IBOutlet private var label: UILabel!",
+            "@IBOutlet var label: UILabel!",
+            "@IBOutlet var label: [UILabel!]",
+            "if !boolean {}",
+            "let int: Int? = 42",
+            "let int: Int? = nil"
+        ],
+        triggeringExamples: [
+            "let label: UILabel!",
+            "let IBOutlet: UILabel!",
+            "let labels: [UILabel!]",
+            "var ints: [Int!] = [42, nil, 42]",
+            "let label: IBOutlet!",
+            "let int: Int! = 42",
+            "let int: Int! = nil",
+            "var int: Int! = 42",
+            "let int: ImplicitlyUnwrappedOptional<Int>",
+            "let collection: AnyCollection<Int!>",
+            "func foo(int: Int!) {}"
+        ]
+    )
+
+    private func hasImplicitlyUnwrappedOptional(_ typeName: String) -> Bool {
+        return typeName.range(of: "!") != nil || typeName.range(of: "ImplicitlyUnwrappedOptional<") != nil
+    }
+
+    public func validate(file: File, kind: SwiftDeclarationKind,
+                         dictionary: [String: SourceKitRepresentable]) -> [StyleViolation] {
+        guard SwiftDeclarationKind.variableKinds().contains(kind) else {
+            return []
+        }
+
+        guard let typeName = dictionary.typeName  else { return [] }
+        guard hasImplicitlyUnwrappedOptional(typeName) else { return [] }
+
+        if configuration.mode == .allExceptIBOutlets {
+            let isOutlet = dictionary.enclosedSwiftAttributes.contains("source.decl.attribute.iboutlet")
+            if isOutlet { return [] }
+        }
+
+        let location: Location
+        if let offset = dictionary.offset {
+            location = Location(file: file, byteOffset: offset)
+        } else {
+            location = Location(file: file.path)
+        }
+
+        return [
+            StyleViolation(ruleDescription: type(of: self).description,
+                           severity: configuration.severity.severity,
+                           location: location)
+        ]
+    }
+
+}

Source/SwiftLintFramework/Rules/RuleConfigurations/ImplicitlyUnwrappedOptionalConfiguration.swift

@@ -0,0 +1,59 @@
+//
+//  ImplicitlyUnwrappedOptionalConfiguration.swift
+//  SwiftLint
+//
+//  Created by Siarhei Fedartsou on 18/03/17.
+//  Copyright © 2017 Realm. All rights reserved.
+//
+
+import Foundation
+
+// swiftlint:disable:next type_name
+public enum ImplicitlyUnwrappedOptionalModeConfiguration: String {
+    case all = "all"
+    case allExceptIBOutlets = "all_except_iboutlets"
+
+    init(value: Any) throws {
+        if let string = (value as? String)?.lowercased(),
+            let value = ImplicitlyUnwrappedOptionalModeConfiguration(rawValue: string) {
+            self = value
+        } else {
+            throw ConfigurationError.unknownConfiguration
+        }
+    }
+}
+
+public struct ImplicitlyUnwrappedOptionalConfiguration: RuleConfiguration, Equatable {
+    private(set) var severity: SeverityConfiguration
+    private(set) var mode: ImplicitlyUnwrappedOptionalModeConfiguration
+
+    init(mode: ImplicitlyUnwrappedOptionalModeConfiguration, severity: SeverityConfiguration) {
+        self.mode = mode
+        self.severity = severity
+    }
+
+    public var consoleDescription: String {
+        return severity.consoleDescription +
+            ", mode: \(mode)"
+    }
+
+    public mutating func apply(configuration: Any) throws {
+        guard let configuration = configuration as? [String: Any] else {
+            throw ConfigurationError.unknownConfiguration
+        }
+
+        if let modeString = configuration["mode"] {
+            try mode = ImplicitlyUnwrappedOptionalModeConfiguration(value: modeString)
+        }
+
+        if let severityString = configuration["severity"] as? String {
+            try severity.apply(configuration: severityString)
+        }
+    }
+
+    public static func == (lhs: ImplicitlyUnwrappedOptionalConfiguration,
+                           rhs: ImplicitlyUnwrappedOptionalConfiguration) -> Bool {
+        return lhs.severity == rhs.severity &&
+            lhs.mode == rhs.mode
+    }
+}

SwiftLint.xcodeproj/project.pbxproj

@@ -49,6 +49,10 @@
 		3BCC04D41C502BAB006073C3 /* RuleConfigurationTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3BCC04D31C502BAB006073C3 /* RuleConfigurationTests.swift */; };
 		3BD9CD3D1C37175B009A5D25 /* YamlParser.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3BD9CD3C1C37175B009A5D25 /* YamlParser.swift */; };
 		3BDB224B1C345B4900473680 /* ProjectMock in Resources */ = {isa = PBXBuildFile; fileRef = 3BDB224A1C345B4900473680 /* ProjectMock */; };
+		47ACC8981E7DC74E0088EEB2 /* ImplicitlyUnwrappedOptionalConfiguration.swift in Sources */ = {isa = PBXBuildFile; fileRef = 47ACC8971E7DC74E0088EEB2 /* ImplicitlyUnwrappedOptionalConfiguration.swift */; };
+		47ACC89A1E7DCCAD0088EEB2 /* ImplicitlyUnwrappedOptionalConfigurationTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 47ACC8991E7DCCAD0088EEB2 /* ImplicitlyUnwrappedOptionalConfigurationTests.swift */; };
+		47ACC89C1E7DCFA00088EEB2 /* ImplicitlyUnwrappedOptionalRuleTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 47ACC89B1E7DCFA00088EEB2 /* ImplicitlyUnwrappedOptionalRuleTests.swift */; };
+		47FF3BE11E7C75B600187E6D /* ImplicitlyUnwrappedOptionalRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = 47FF3BDF1E7C745100187E6D /* ImplicitlyUnwrappedOptionalRule.swift */; };
 		4A9A3A3A1DC1D75F00DF5183 /* HTMLReporter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4A9A3A391DC1D75F00DF5183 /* HTMLReporter.swift */; };
 		4DB7815E1CAD72BA00BC4723 /* LegacyCGGeometryFunctionsRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4DB7815C1CAD690100BC4723 /* LegacyCGGeometryFunctionsRule.swift */; };
 		4DCB8E7F1CBE494E0070FCF0 /* RegexHelpers.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4DCB8E7D1CBE43640070FCF0 /* RegexHelpers.swift */; };
@@ -311,6 +315,10 @@
 		3BCC04D31C502BAB006073C3 /* RuleConfigurationTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RuleConfigurationTests.swift; sourceTree = "<group>"; };
 		3BD9CD3C1C37175B009A5D25 /* YamlParser.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = YamlParser.swift; sourceTree = "<group>"; };
 		3BDB224A1C345B4900473680 /* ProjectMock */ = {isa = PBXFileReference; lastKnownFileType = folder; path = ProjectMock; sourceTree = "<group>"; };
+		47ACC8971E7DC74E0088EEB2 /* ImplicitlyUnwrappedOptionalConfiguration.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ImplicitlyUnwrappedOptionalConfiguration.swift; sourceTree = "<group>"; };
+		47ACC8991E7DCCAD0088EEB2 /* ImplicitlyUnwrappedOptionalConfigurationTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ImplicitlyUnwrappedOptionalConfigurationTests.swift; sourceTree = "<group>"; };
+		47ACC89B1E7DCFA00088EEB2 /* ImplicitlyUnwrappedOptionalRuleTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ImplicitlyUnwrappedOptionalRuleTests.swift; sourceTree = "<group>"; };
+		47FF3BDF1E7C745100187E6D /* ImplicitlyUnwrappedOptionalRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ImplicitlyUnwrappedOptionalRule.swift; sourceTree = "<group>"; };
 		4A9A3A391DC1D75F00DF5183 /* HTMLReporter.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = HTMLReporter.swift; sourceTree = "<group>"; };
 		4DB7815C1CAD690100BC4723 /* LegacyCGGeometryFunctionsRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = LegacyCGGeometryFunctionsRule.swift; sourceTree = "<group>"; };
 		4DCB8E7D1CBE43640070FCF0 /* RegexHelpers.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RegexHelpers.swift; sourceTree = "<group>"; };
@@ -557,6 +565,7 @@
 				D43B04671E07228D004016AF /* ColonConfiguration.swift */,
 				67EB4DF81E4CC101004E9ACD /* CyclomaticComplexityConfiguration.swift */,
 				D4C4A3511DEFBBB700E0E04C /* FileHeaderConfiguration.swift */,
+				47ACC8971E7DC74E0088EEB2 /* ImplicitlyUnwrappedOptionalConfiguration.swift */,
 				3B034B6C1E0BE544005D49A9 /* LineLengthConfiguration.swift */,
 				3BCC04D01C4F56D3006073C3 /* NameConfiguration.swift */,
 				D93DA3CF1E699E4E00809827 /* NestingConfiguration.swift */,
@@ -759,6 +768,8 @@
 				006204DD1E1E4E0A00FFFBE1 /* VerticalWhitespaceRuleTests.swift */,
 				67EB4DFB1E4CD7F5004E9ACD /* CyclomaticComplexityRuleTests.swift */,
 				67932E2C1E54AF4B00CB0629 /* CyclomaticComplexityConfigurationTests.swift */,
+				47ACC8991E7DCCAD0088EEB2 /* ImplicitlyUnwrappedOptionalConfigurationTests.swift */,
+				47ACC89B1E7DCFA00088EEB2 /* ImplicitlyUnwrappedOptionalRuleTests.swift */,
 			);
 			name = SwiftLintFrameworkTests;
 			path = Tests/SwiftLintFrameworkTests;
@@ -842,6 +853,7 @@
 				E88DEA931B099C0900A66CB0 /* IdentifierNameRule.swift */,
 				D4130D961E16183F00242361 /* IdentifierNameRuleExamples.swift */,
 				D43DB1071DC573DA00281215 /* ImplicitGetterRule.swift */,
+				47FF3BDF1E7C745100187E6D /* ImplicitlyUnwrappedOptionalRule.swift */,
 				D4DA1DF91E18D6200037413D /* LargeTupleRule.swift */,
 				E88DEA7D1B098F2A00A66CB0 /* LeadingWhitespaceRule.swift */,
 				4DB7815C1CAD690100BC4723 /* LegacyCGGeometryFunctionsRule.swift */,
@@ -1185,6 +1197,7 @@
 				3BCC04CD1C4F5694006073C3 /* ConfigurationError.swift in Sources */,
 				D4C4A34E1DEA877200E0E04C /* FileHeaderRule.swift in Sources */,
 				009E092A1DFEE4DD00B588A7 /* ProhibitedSuperConfiguration.swift in Sources */,
+				47FF3BE11E7C75B600187E6D /* ImplicitlyUnwrappedOptionalRule.swift in Sources */,
 				BFF028AE1CBCF8A500B38A9D /* TrailingWhitespaceConfiguration.swift in Sources */,
 				3B034B6E1E0BE549005D49A9 /* LineLengthConfiguration.swift in Sources */,
 				D4C4A34C1DEA4FF000E0E04C /* AttributesConfiguration.swift in Sources */,
@@ -1239,6 +1252,7 @@
 				D43B04691E072291004016AF /* ColonConfiguration.swift in Sources */,
 				D4130D991E16CC1300242361 /* TypeNameRuleExamples.swift in Sources */,
 				24E17F721B14BB3F008195BE /* File+Cache.swift in Sources */,
+				47ACC8981E7DC74E0088EEB2 /* ImplicitlyUnwrappedOptionalConfiguration.swift in Sources */,
 				009E09281DFEE4C200B588A7 /* ProhibitedSuperRule.swift in Sources */,
 				E80E018F1B92C1350078EB70 /* Region.swift in Sources */,
 				E88198581BEA956C00333A11 /* FunctionBodyLengthRule.swift in Sources */,
@@ -1329,6 +1343,7 @@
 				E832F10D1B17E725003F265F /* IntegrationTests.swift in Sources */,
 				D4C27C001E12DFF500DF713E /* LinterCacheTests.swift in Sources */,
 				D4998DE91DF194F20006E05D /* FileHeaderRuleTests.swift in Sources */,
+				47ACC89C1E7DCFA00088EEB2 /* ImplicitlyUnwrappedOptionalRuleTests.swift in Sources */,
 				006204DE1E1E4E0A00FFFBE1 /* VerticalWhitespaceRuleTests.swift in Sources */,
 				02FD8AEF1BFC18D60014BFFB /* ExtendedNSStringTests.swift in Sources */,
 				D4CA758F1E2DEEA500A40E8A /* NumberSeparatorRuleTests.swift in Sources */,
@@ -1345,6 +1360,7 @@
 				3B30C4A11C3785B300E04027 /* YamlParserTests.swift in Sources */,
 				D4998DE71DF191380006E05D /* AttributesRuleTests.swift in Sources */,
 				E88198631BEA9A5400333A11 /* RulesTests.swift in Sources */,
+				47ACC89A1E7DCCAD0088EEB2 /* ImplicitlyUnwrappedOptionalConfigurationTests.swift in Sources */,
 				D46202211E16002A0027AAD1 /* Swift2RulesTests.swift in Sources */,
 				67932E2D1E54AF4B00CB0629 /* CyclomaticComplexityConfigurationTests.swift in Sources */,
 				C9802F2F1E0C8AEE008AB27F /* TrailingCommaRuleTests.swift in Sources */,

Tests/SwiftLintFrameworkTests/ImplicitlyUnwrappedOptionalConfigurationTests.swift

@@ -0,0 +1,64 @@
+//
+//  ImplicitlyUnwrappedOptionalConfigurationTests.swift
+//  SwiftLint
+//
+//  Created by Siarhei Fedartsou on 18/03/17.
+//  Copyright © 2017 Realm. All rights reserved.
+//
+
+import SourceKittenFramework
+@testable import SwiftLintFramework
+import XCTest
+
+// swiftlint:disable:next type_name
+class ImplicitlyUnwrappedOptionalConfigurationTests: XCTestCase {
+
+    func testImplicitlyUnwrappedOptionalConfigurationProperlyAppliesConfigurationFromDictionary() throws {
+        var configuration = ImplicitlyUnwrappedOptionalConfiguration(mode: .allExceptIBOutlets,
+                                                                     severity: SeverityConfiguration(.warning))
+
+        try configuration.apply(configuration: ["mode": "all", "severity": "error"])
+        XCTAssertEqual(configuration.mode, .all)
+        XCTAssertEqual(configuration.severity.severity, .error)
+
+        try configuration.apply(configuration: ["mode": "all_except_iboutlets"])
+        XCTAssertEqual(configuration.mode, .allExceptIBOutlets)
+        XCTAssertEqual(configuration.severity.severity, .error)
+
+        try configuration.apply(configuration: ["severity": "warning"])
+        XCTAssertEqual(configuration.mode, .allExceptIBOutlets)
+        XCTAssertEqual(configuration.severity.severity, .warning)
+
+        try configuration.apply(configuration: ["mode": "all", "severity": "warning"])
+        XCTAssertEqual(configuration.mode, .all)
+        XCTAssertEqual(configuration.severity.severity, .warning)
+    }
+
+    func testImplicitlyUnwrappedOptionalConfigurationThrowsOnBadConfig() {
+        let badConfigs: [[String: Any]] = [
+            ["mode": "everything"],
+            ["mode": false],
+            ["mode": 42]
+        ]
+
+        for badConfig in badConfigs {
+            var configuration = ImplicitlyUnwrappedOptionalConfiguration(mode: .allExceptIBOutlets,
+                                                                         severity: SeverityConfiguration(.warning))
+            checkError(ConfigurationError.unknownConfiguration) {
+                try configuration.apply(configuration: badConfig)
+            }
+        }
+    }
+
+}
+
+extension ImplicitlyUnwrappedOptionalConfigurationTests {
+    static var allTests: [(String, (ImplicitlyUnwrappedOptionalConfigurationTests) -> () throws -> Void)] {
+        return [
+            ("testImplicitlyUnwrappedOptionalConfigurationProperlyAppliesConfigurationFromDictionary",
+             testImplicitlyUnwrappedOptionalConfigurationProperlyAppliesConfigurationFromDictionary),
+            ("testImplicitlyUnwrappedOptionalConfigurationThrowsOnBadConfig",
+             testImplicitlyUnwrappedOptionalConfigurationThrowsOnBadConfig)
+        ]
+    }
+}

Tests/SwiftLintFrameworkTests/ImplicitlyUnwrappedOptionalRuleTests.swift

@@ -0,0 +1,50 @@
+//
+//  ImplicitlyUnwrappedOptionalRuleTests.swift
+//  SwiftLint
+//
+//  Created by Siarhei Fedartsou on 18/03/17.
+//  Copyright © 2017 Realm. All rights reserved.
+//
+
+import Foundation
+@testable import SwiftLintFramework
+import XCTest
+
+class ImplicitlyUnwrappedOptionalRuleTests: XCTestCase {
+
+    func testImplicitlyUnwrappedOptionalRuleDefaultConfiguration() {
+        let rule = ImplicitlyUnwrappedOptionalRule()
+        XCTAssertEqual(rule.configuration.mode, .allExceptIBOutlets)
+        XCTAssertEqual(rule.configuration.severity.severity, .warning)
+    }
+
+    func testImplicitlyUnwrappedOptionalRuleWarnsOnOutletsInAllMode() {
+        let baseDescription = ImplicitlyUnwrappedOptionalRule.description
+        let triggeringExamples = [
+            "@IBOutlet private var label: UILabel!",
+            "@IBOutlet var label: UILabel!",
+            "let int: Int!"
+        ]
+
+        let nonTriggeringExamples = ["if !boolean {}"]
+        let description = RuleDescription(identifier: baseDescription.identifier,
+                                          name: baseDescription.name,
+                                          description: baseDescription.description,
+                                          nonTriggeringExamples: nonTriggeringExamples,
+                                          triggeringExamples: triggeringExamples,
+                                          corrections: baseDescription.corrections)
+        verifyRule(description, ruleConfiguration: ["mode": "all"],
+                   commentDoesntViolate: true, stringDoesntViolate: true)
+    }
+}
+
+extension ImplicitlyUnwrappedOptionalRuleTests {
+    static var allTests: [(String, (ImplicitlyUnwrappedOptionalRuleTests) -> () throws -> Void)] {
+        return [
+            ("testImplicitlyUnwrappedOptionalRuleDefaultConfiguration",
+             testImplicitlyUnwrappedOptionalRuleDefaultConfiguration),
+            ("testImplicitlyUnwrappedOptionalRuleWarnsOnOutletsInAllMode",
+             testImplicitlyUnwrappedOptionalRuleWarnsOnOutletsInAllMode)
+        ]
+    }
+}

Tests/SwiftLintFrameworkTests/RulesTests.swift

@@ -121,6 +121,10 @@ class RulesTests: XCTestCase {
         verifyRule(ImplicitGetterRule.description)
     }
 
+    func testImplicitlyUnwrappedOptional() {
+        verifyRule(ImplicitlyUnwrappedOptionalRule.description)
+    }
+
     func testLargeTuple() {
         verifyRule(LargeTupleRule.description)
     }
@@ -378,6 +382,7 @@ extension RulesTests {
             ("testGenericTypeName", testGenericTypeName),
             ("testIdentifierName", testIdentifierName),
             ("testImplicitGetter", testImplicitGetter),
+            ("testImplicitlyUnwrappedOptional", testImplicitlyUnwrappedOptional),
             ("testLargeTuple", testLargeTuple),
             ("testLeadingWhitespace", testLeadingWhitespace),
             ("testLegacyCGGeometryFunctions", testLegacyCGGeometryFunctions),