Implement DontRepeatTypeInStaticProperties rule and tests. (swiftlang#78)

Author: LaurenWhite

tools/swift-format/Sources/Rules/DontRepeatTypeInStaticProperties.swift

@@ -12,5 +12,77 @@ import SwiftSyntax
 ///
 /// - SeeAlso: https://google.github.io/swift#static-and-class-properties
 public final class DontRepeatTypeInStaticProperties: SyntaxLintRule {
+  
+  public override func visit(_ node: ClassDeclSyntax) {
+    determinePropertyNameViolations(members: node.members.members, nodeId: node.identifier.text)
+  }
+  
+  public override func visit(_ node: EnumDeclSyntax) {
+    determinePropertyNameViolations(members: node.members.members, nodeId: node.identifier.text)
+  }
+  
+  public override func visit(_ node: ProtocolDeclSyntax) {
+    determinePropertyNameViolations(members: node.members.members, nodeId: node.identifier.text)
+  }
+  
+  public override func visit(_ node: StructDeclSyntax) {
+    determinePropertyNameViolations(members: node.members.members, nodeId: node.identifier.text)
+  }
+  
+  public override func visit(_ node: ExtensionDeclSyntax) {
+    determinePropertyNameViolations(members: node.members.members, nodeId: node.extendedType.description)
+  }
+  
+  func determinePropertyNameViolations(members: MemberDeclListSyntax, nodeId: String) {
+    for member in members {
+      guard let decl = member.decl as? VariableDeclSyntax else { continue }
+      guard let modifiers = decl.modifiers else { continue }
+      guard containsClassOrStatic(modifiers: modifiers) else { continue }
+      
+      let typeName = withoutPrefix(name: nodeId)
+      var varName = ""
+      
+      for binding in decl.bindings {
+        guard let exp = binding.pattern as? IdentifierPatternSyntax else { continue }
+        varName = exp.identifier.text
+      }
+      
+      if varName.contains(typeName) {
+        diagnose(.removeTypeFromName(name: varName, type: typeName), on: decl)
+      }
+    }
+  }
+  
+  func containsClassOrStatic(modifiers: ModifierListSyntax) -> Bool {
+    for modifier in modifiers {
+      let name = modifier.name.text
+      if name == "class" || name == "static" { return true }
+    }
+    return false
+  }
+  
+  // Returns the given string without capitalized prefix in the beginning
+  func withoutPrefix(name: String) -> String {
+    let formattedName = name.trimmingCharacters(in: CharacterSet.whitespaces)
+    let upperCase = Array(formattedName.uppercased())
+    let original = Array(formattedName)
+    guard original[0] == upperCase[0] else { return name }
+    
+    var prefixEndsAt = 0
+    var idx = 0
+    while idx <= name.count - 2 {
+      if original[idx] == upperCase[idx] &&
+         original[idx + 1] != upperCase[idx + 1] {
+        prefixEndsAt = idx
+      }
+      idx += 1
+    }
+    return String(formattedName.dropFirst(prefixEndsAt))
+  }
+}
 
+extension Diagnostic.Message {
+  static func removeTypeFromName(name: String, type: String) -> Diagnostic.Message {
+    return .init(.warning, "Remove '\(type)' from '\(name)'")
+  }
 }

tools/swift-format/Tests/SwiftFormatTests/DontRepeatTypeInStaticPropertiesTests.swift

@@ -0,0 +1,65 @@
+import Foundation
+import SwiftSyntax
+import XCTest
+
+@testable import Rules
+
+public class DontRepeatTypeInStaticPropertiesTests: DiagnosingTestCase {
+  public func testRepetitiveProperties() {
+    let input =
+    """
+    public class UIColor {
+      static let redColor: UIColor
+      public class var blueColor: UIColor
+      var yellowColor: UIColor
+      static let green: UIColor
+      public class var purple: UIColor
+    }
+    enum Sandwich {
+      static let bolognaSandwich: Sandwich
+      static var hamSandwich: Sandwich
+      static var turkey: Sandwich
+    }
+    protocol RANDPerson {
+      var oldPerson: Person
+      static let youngPerson: Person
+    }
+    struct TVGame {
+      static var basketballGame: TVGame
+      static var baseballGame: TVGame
+      static let soccer: TVGame
+      let hockey: TVGame
+    }
+    extension URLSession {
+      class var sharedSession: URLSession
+    }
+    """
+    performLint(DontRepeatTypeInStaticProperties.self, input: input)
+    XCTAssertDiagnosed(.removeTypeFromName(name: "redColor", type: "Color"))
+    XCTAssertDiagnosed(.removeTypeFromName(name: "blueColor", type: "Color"))
+    XCTAssertNotDiagnosed(.removeTypeFromName(name: "yellowColor", type: "Color"))
+    XCTAssertNotDiagnosed(.removeTypeFromName(name: "green", type: "Color"))
+    XCTAssertNotDiagnosed(.removeTypeFromName(name: "purple", type: "Color"))
+    
+    XCTAssertDiagnosed(.removeTypeFromName(name: "bolognaSandwich", type: "Sandwich"))
+    XCTAssertDiagnosed(.removeTypeFromName(name: "hamSandwich", type: "Sandwich"))
+    XCTAssertNotDiagnosed(.removeTypeFromName(name: "turkey", type: "Sandwich"))
+    
+    XCTAssertNotDiagnosed(.removeTypeFromName(name: "oldPerson", type: "Person"))
+    XCTAssertDiagnosed(.removeTypeFromName(name: "youngPerson", type: "Person"))
+    
+    XCTAssertDiagnosed(.removeTypeFromName(name: "basketballGame", type: "Game"))
+    XCTAssertDiagnosed(.removeTypeFromName(name: "baseballGame", type: "Game"))
+    XCTAssertNotDiagnosed(.removeTypeFromName(name: "soccer", type: "Game"))
+    XCTAssertNotDiagnosed(.removeTypeFromName(name: "hockey", type: "Game"))
+    
+    XCTAssertDiagnosed(.removeTypeFromName(name: "sharedSession", type: "Session"))
+  }
+  
+  #if !os(macOS)
+  static let allTests = [
+    DontRepeatTypeInStaticPropertiesTests.testRepetitiveProperties,
+    ]
+  #endif
+}
+