Implement NoLeadingUnderscores rule and tests. (swiftlang#54)

Author: LaurenWhite

Sources/Rules/NoLeadingUnderscores.swift

@@ -11,5 +11,105 @@ import SwiftSyntax
 ///
 /// - SeeAlso: https://google.github.io/swift#naming-conventions-are-not-access-control
 public final class NoLeadingUnderscores: SyntaxLintRule {
+  
+  public override func visit(_ node: AssociatedtypeDeclSyntax) {
+    diagnoseUnderscoreViolation(name: node.identifier)
+  }
+  
+  public override func visit(_ node: ClassDeclSyntax) {
+    diagnoseUnderscoreViolation(name: node.identifier)
+    super.visit(node) // Visit children despite override
+  }
+  
+  public override func visit(_ node: EnumDeclSyntax) {
+    diagnoseUnderscoreViolation(name: node.identifier)
+    super.visit(node)
+  }
+  
+  public override func visit(_ node: EnumCaseDeclSyntax) {
+    for element in node.elements {
+      diagnoseUnderscoreViolation(name: element.identifier)
+    }
+  }
+  
+  public override func visit(_ node: FunctionDeclSyntax) {
+    diagnoseUnderscoreViolation(name: node.identifier)
+    // Check parameter names of function
+    let parameters = node.signature.input.parameterList
+    for parameter in parameters {
+      if let typeIdentifier = parameter.firstName {
+        diagnoseUnderscoreViolation(name: typeIdentifier)
+      }
+      if let varIdentifier = parameter.secondName {
+        diagnoseUnderscoreViolation(name: varIdentifier)
+      }
+    }
+    // Check generic parameter names
+    if let genParameters = node.genericParameterClause?.genericParameterList {
+      for genParameter in genParameters {
+        diagnoseUnderscoreViolation(name: genParameter.name)
+      }
+    }
+    super.visit(node)
+  }
+  
+  public override func visit(_ node: PrecedenceGroupDeclSyntax) {
+    diagnoseUnderscoreViolation(name: node.identifier)
+  }
+  
+  public override func visit(_ node: ProtocolDeclSyntax) {
+    diagnoseUnderscoreViolation(name: node.identifier)
+    super.visit(node)
+  }
+  
+  public override func visit(_ node: StructDeclSyntax) {
+    diagnoseUnderscoreViolation(name: node.identifier)
+    // Check generic parameter names
+    if let genParameters = node.genericParameterClause?.genericParameterList {
+      for genParameter in genParameters {
+        diagnoseUnderscoreViolation(name: genParameter.name)
+      }
+    }
+    super.visit(node)
+  }
+  
+  public override func visit(_ node: TypealiasDeclSyntax) {
+    diagnoseUnderscoreViolation(name: node.identifier)
+  }
+  
+  public override func visit(_ node: InitializerDeclSyntax) {
+    // Check parameter names of initializer
+    let parameters = node.parameters.parameterList
+    for parameter in parameters {
+      if let typeIdentifier = parameter.firstName {
+        diagnoseUnderscoreViolation(name: typeIdentifier)
+      }
+      if let varIdentifier = parameter.secondName {
+        diagnoseUnderscoreViolation(name: varIdentifier)
+      }
+    }
+    super.visit(node)
+  }
+  
+  public override func visit(_ node: VariableDeclSyntax) {
+    for binding in node.bindings {
+      if let pat = binding.pattern as? IdentifierPatternSyntax {
+        diagnoseUnderscoreViolation(name: pat.identifier)
+      }
+    }
+    super.visit(node)
+  }
+  
+  func diagnoseUnderscoreViolation(name: TokenSyntax) {
+    let leadingChar = name.text.first
+    if leadingChar == "_" {
+      diagnose(.doNotLeadWithUnderscore(identifier: name.text), on: name)
+    }
+  }
+}
 
+extension Diagnostic.Message {
+  static func doNotLeadWithUnderscore(identifier: String) -> Diagnostic.Message {
+    return .init(.warning, "Identifier \(identifier) should not lead with '_'")
+  }
 }

Tests/SwiftFormatTests/NoLeadingUnderscoresTests.swift

@@ -0,0 +1,100 @@
+import Foundation
+import SwiftSyntax
+import XCTest
+
+@testable import Rules
+
+public class NoLeadingUnderscoresTests: DiagnosingTestCase {
+  public func testInvalidIdentifierNames() {
+    let input =
+    """
+      let _foo = foo
+      var good_name = 20
+      var _badName, okayName, _wor_sEName = 20
+      struct _baz {
+        var x: Int {
+          get {
+            var a = 10
+            var _b = 20
+          }
+          set {
+            var _c = 10
+            var d = 20
+          }
+        }
+
+        init(foox z: Int, bar _y: Int) {}
+        func _bazFunc(arg1: String, _arg2: Int) {}
+        func quuxFunc(fooo _x: Int) {}
+      }
+
+      protocol _SomeProtocol {
+        func _food()
+      }
+
+      struct Bag<_Element> {}
+      func generic<_Arg>(x: _Arg) {}
+
+      enum Numbers {
+        case one
+        case _two
+        case three
+      }
+
+      func f() {
+        var _x: Int = 10
+        var y: Int = 20
+      }
+    """
+    performLint(NoLeadingUnderscores.self, input: input)
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_foo"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "good_name"))
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_badName"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "okayName"))
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_wor_sEName"))
+    
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_baz"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "x"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "a"))
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_b"))
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_c"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "d"))
+    
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "init"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "foox"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "z"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "bar"))
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_y"))
+    
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_bazFunc"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "arg1"))
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_arg2"))
+    
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "quuxFunc"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "fooo"))
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_x"))
+    
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_SomeProtocol"))
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_food"))
+    
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_Element"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "generic"))
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_Arg"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "x"))
+    
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "Numbers"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "one"))
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_two"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "three"))
+    
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "f"))
+    XCTAssertDiagnosed(.doNotLeadWithUnderscore(identifier: "_x"))
+    XCTAssertNotDiagnosed(.doNotLeadWithUnderscore(identifier: "y"))
+  }
+    
+#if !os(macOS)
+  static let allTests = [
+    NoLeadingUnderscores.testInvalidIdentifierNames,
+  ]
+#endif
+}