Get rid of @testable import

Author: SimplyDanny

.swiftlint.yml

@@ -110,7 +110,7 @@ custom_rules:
   fatal_error:
     name: Fatal Error
     excluded: "Tests/*"
-    message: Prefer using `queuedFatalError` over `fatalError` to avoid leaking compiler host machine paths.
+    message: Prefer `queuedFatalError` over `fatalError` to avoid leaking compiler host machine paths
     regex: \bfatalError\b
     match_kinds:
       - identifier
@@ -121,3 +121,9 @@ custom_rules:
     message: Rule Test Function mustn't end with `rule`
     regex: func\s*test\w+(r|R)ule\(\)
     severity: error
+  testable_import:
+    included: Tests/TestHelpers/.+\.swift
+    name: Testable Import
+    message: Do not use @testable imports
+    regex: ^\s*@testable\s+import\s+\w+
+    severity: error

Source/SwiftLintCoreMacros/DisabledWithoutSourceKit.swift

@@ -14,12 +14,15 @@ enum DisabledWithoutSourceKit: ExtensionMacro {
             context.diagnose(SwiftLintCoreMacroError.notStruct.diagnose(at: declaration))
             return []
         }
+        let acl = declaration.modifiers.first {
+            ["public", "internal", "package", "fileprivate", "private"].contains($0.name.text)
+        }?.name.text ?? "internal"
         let message = #"""
         "Skipping enabled rule '\(Self.identifier)' because it requires SourceKit and SourceKit access is prohibited."
         """#
         return [
             try ExtensionDeclSyntax("""
-                extension \(type) {
+                \(raw: acl) extension \(type) {
                     private static let postMessage: Void = {
                         Issue.genericWarning(\(raw: message)).print()
                     }()

Source/SwiftLintFramework/Rules/CustomRules.swift

@@ -2,11 +2,11 @@ import Foundation
 
 // MARK: - CustomRulesConfiguration
 
-struct CustomRulesConfiguration: RuleConfiguration, CacheDescriptionProvider {
-    typealias Parent = CustomRules
+package struct CustomRulesConfiguration: RuleConfiguration, CacheDescriptionProvider {
+    package typealias Parent = CustomRules
 
-    var parameterDescription: RuleConfigurationDescription? { RuleConfigurationOption.noOptions }
-    var cacheDescription: String {
+    package var parameterDescription: RuleConfigurationDescription? { RuleConfigurationOption.noOptions }
+    package var cacheDescription: String {
         let configsDescription = customRuleConfigurations
             .sorted { $0.identifier < $1.identifier }
             .map(\.cacheDescription)
@@ -20,7 +20,7 @@ struct CustomRulesConfiguration: RuleConfiguration, CacheDescriptionProvider {
     var customRuleConfigurations = [RegexConfiguration<Parent>]()
     var defaultExecutionMode: RegexConfiguration<Parent>.ExecutionMode?
 
-    mutating func apply(configuration: Any) throws(Issue) {
+    package mutating func apply(configuration: Any) throws(Issue) {
         guard let configurationDict = configuration as? [String: Any] else {
             throw .invalidConfiguration(ruleID: Parent.identifier)
         }
@@ -52,16 +52,20 @@ struct CustomRulesConfiguration: RuleConfiguration, CacheDescriptionProvider {
 // MARK: - CustomRules
 
 @DisabledWithoutSourceKit
-struct CustomRules: Rule, CacheDescriptionProvider, ConditionallySourceKitFree {
-    var cacheDescription: String {
+package struct CustomRules: Rule, CacheDescriptionProvider, ConditionallySourceKitFree {
+    package init() {
+        // Nothing to initialize.
+    }
+
+    package var cacheDescription: String {
         configuration.cacheDescription
     }
 
     var customRuleIdentifiers: [String] {
         configuration.customRuleConfigurations.map(\.identifier)
     }
 
-    static let description = RuleDescription(
+    package static let description = RuleDescription(
         identifier: "custom_rules",
         name: "Custom Rules",
         description: """
@@ -71,10 +75,10 @@ struct CustomRules: Rule, CacheDescriptionProvider, ConditionallySourceKitFree {
             """,
         kind: .style)
 
-    var configuration = CustomRulesConfiguration()
+    package var configuration = CustomRulesConfiguration()
 
     /// Returns true if all configured custom rules use SwiftSyntax mode, making this rule effectively SourceKit-free.
-    var isEffectivelySourceKitFree: Bool {
+    package var isEffectivelySourceKitFree: Bool {
         configuration.customRuleConfigurations.allSatisfy { config in
             let effectiveMode = config.executionMode == .default
                 ? (configuration.defaultExecutionMode ?? .sourcekit)
@@ -83,7 +87,7 @@ struct CustomRules: Rule, CacheDescriptionProvider, ConditionallySourceKitFree {
         }
     }
 
-    func validate(file: SwiftLintFile) -> [StyleViolation] {
+    package func validate(file: SwiftLintFile) -> [StyleViolation] {
         var configurations = configuration.customRuleConfigurations
 
         guard configurations.isNotEmpty else {
@@ -114,7 +118,7 @@ struct CustomRules: Rule, CacheDescriptionProvider, ConditionallySourceKitFree {
         }
     }
 
-    func canBeDisabled(violation: StyleViolation, by ruleID: RuleIdentifier) -> Bool {
+    package func canBeDisabled(violation: StyleViolation, by ruleID: RuleIdentifier) -> Bool {
         switch ruleID {
         case let .single(identifier: id):
             id == Self.identifier
@@ -125,7 +129,7 @@ struct CustomRules: Rule, CacheDescriptionProvider, ConditionallySourceKitFree {
         }
     }
 
-    func isEnabled(in region: Region, for ruleID: String) -> Bool {
+    package func isEnabled(in region: Region, for ruleID: String) -> Bool {
         if !Self.description.allIdentifiers.contains(ruleID),
            !customRuleIdentifiers.contains(ruleID),
            Self.identifier != ruleID {

Tests/TestHelpers/TestHelpers.swift

@@ -2,7 +2,7 @@ import Foundation
 import SourceKittenFramework
 import XCTest
 
-@testable import SwiftLintFramework
+import SwiftLintFramework
 
 // swiftlint:disable file_length
 
@@ -582,7 +582,7 @@ private extension RuleDescription {
     }
 }
 
-public extension [any Rule] {
+package extension [any Rule] {
     var customRules: CustomRules? {
         first(where: { $0 is CustomRules }) as? CustomRules
     }