Clean up XCTest import state representation.

Author: allevato

Sources/SwiftFormatCore/Context.swift

@@ -19,6 +19,21 @@ import SwiftSyntax
 /// Specifically, it is the container for the shared configuration, diagnostic engine, and URL of
 /// the current file.
 public class Context {
+
+  /// Tracks whether `XCTest` has been imported so that certain logic can be modified for files that
+  /// are known to be tests.
+  public enum XCTestImportState {
+
+    /// Whether `XCTest` is imported or not has not yet been determined.
+    case notDetermined
+
+    /// The file is known to import `XCTest`.
+    case importsXCTest
+
+    /// The file is known to not import `XCTest`.
+    case doesNotImportXCTest
+  }
+
   /// The configuration for this run of the pipeline, provided by a configuration JSON file.
   public let configuration: Configuration
 
@@ -28,11 +43,8 @@ public class Context {
   /// The URL of the file being linted or formatted.
   public let fileURL: URL
 
-  /// Indicates whether the file imports XCTest, and is test code
-  public var importsXCTest: Bool
-
-  /// Indicates whether the visitor has already determined a value for importsXCTest
-  public var didSetImportsXCTest: Bool
+  /// Indicates whether the file is known to import XCTest.
+  public var importsXCTest: XCTestImportState
 
   /// An object that converts `AbsolutePosition` values to `SourceLocation` values.
   public let sourceLocationConverter: SourceLocationConverter
@@ -50,8 +62,7 @@ public class Context {
     self.configuration = configuration
     self.diagnosticEngine = diagnosticEngine
     self.fileURL = fileURL
-    self.importsXCTest = false
-    self.didSetImportsXCTest = false
+    self.importsXCTest = .notDetermined
     self.sourceLocationConverter = SourceLocationConverter(
       file: fileURL.path, tree: sourceFileSyntax)
     self.ruleMask = RuleMask(

Sources/SwiftFormatRules/ImportsXCTestVisitor.swift

@@ -27,12 +27,11 @@ private struct ImportsXCTestVisitor: SyntaxVisitor {
       guard let importDecl = statement.item as? ImportDeclSyntax else { continue }
       for component in importDecl.path {
         guard component.name.text == "XCTest" else { continue }
-        context.importsXCTest = true
-        context.didSetImportsXCTest = true
+        context.importsXCTest = .importsXCTest
         return .skipChildren
       }
     }
-    context.didSetImportsXCTest = true
+    context.importsXCTest = .doesNotImportXCTest
     return .skipChildren
   }
 }
@@ -47,7 +46,7 @@ private struct ImportsXCTestVisitor: SyntaxVisitor {
 ///   - context: The context information of the target source file.
 ///   - sourceFile: The file to be visited.
 func setImportsXCTest(context: Context, sourceFile: SourceFileSyntax) {
-  guard !context.didSetImportsXCTest else { return }
+  guard context.importsXCTest == .notDetermined else { return }
   var visitor = ImportsXCTestVisitor(context: context)
   sourceFile.walk(&visitor)
 }

Sources/SwiftFormatRules/NeverForceUnwrap.swift

@@ -34,15 +34,15 @@ public struct NeverForceUnwrap: SyntaxLintRule {
   }
 
   public func visit(_ node: ForcedValueExprSyntax) -> SyntaxVisitorContinueKind {
-    guard !context.importsXCTest else { return .skipChildren }
+    guard context.importsXCTest == .doesNotImportXCTest else { return .skipChildren }
     diagnose(.doNotForceUnwrap(name: node.expression.description), on: node)
     return .skipChildren
   }
 
   public func visit(_ node: AsExprSyntax) -> SyntaxVisitorContinueKind {
     // Only fire if we're not in a test file and if there is an exclamation mark following the `as`
     // keyword.
-    guard !context.importsXCTest else { return .skipChildren }
+    guard context.importsXCTest == .doesNotImportXCTest else { return .skipChildren }
     guard let questionOrExclamation = node.questionOrExclamationMark else { return .skipChildren }
     guard questionOrExclamation.tokenKind == .exclamationMark else { return .skipChildren }
     diagnose(.doNotForceCast(name: node.typeName.description), on: node)

Sources/SwiftFormatRules/NeverUseForceTry.swift

@@ -41,7 +41,7 @@ public struct NeverUseForceTry: SyntaxLintRule {
     // TODO: Generalize the `isRuleDisabled` check so it doesn't need to be performed manually for
     // each rule.
     guard !context.isRuleDisabled(self.ruleName, node: node) else { return .visitChildren }
-    guard !context.importsXCTest else { return .skipChildren }
+    guard context.importsXCTest == .doesNotImportXCTest else { return .skipChildren }
     guard let mark = node.questionOrExclamationMark else { return .visitChildren }
     if mark.tokenKind == .exclamationMark {
       diagnose(.doNotForceTry, on: node.tryKeyword)

Sources/SwiftFormatRules/NeverUseImplicitlyUnwrappedOptionals.swift

@@ -41,7 +41,7 @@ public struct NeverUseImplicitlyUnwrappedOptionals: SyntaxLintRule {
   }
 
   public func visit(_ node: VariableDeclSyntax) -> SyntaxVisitorContinueKind {
-    guard !context.importsXCTest else { return .skipChildren }
+    guard context.importsXCTest == .doesNotImportXCTest else { return .skipChildren }
     // Ignores IBOutlet variables
     if let attributes = node.attributes {
       for attribute in attributes {