ValidateSyntaxNodes.swift

//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

import SyntaxSupport
import XCTest

fileprivate func assertNoFailures(
  _ failures: [ValidationFailure],
  message: String,
  file: StaticString = #filePath,
  line: UInt = #line
) {
  if failures.isEmpty {
    return
  }
  var message = "\(message): \n"
  let failuresByNode = [SyntaxNodeKind: [ValidationFailure]](failures.map({ ($0.node, [$0]) })) { $0 + $1 }

  for (nodeKind, failures) in failuresByNode.sorted(by: { $0.key.rawValue < $1.key.rawValue }) {
    message += "\(nodeKind.syntaxType):\n"
    for failure in failures {
      message += "  - \(failure.message)\n"
    }
  }
  XCTFail(message, file: file, line: line)
}

fileprivate func assertFailuresMatchXFails(
  _ failures: [ValidationFailure],
  expectedFailures: [ValidationFailure],
  file: StaticString = #filePath,
  line: UInt = #line
) {
  let matchedXFails = expectedFailures.filter { failures.contains($0) }
  let failures = failures.filter { !matchedXFails.contains($0) }
  let unmatchedXFails = expectedFailures.filter { !matchedXFails.contains($0) }

  assertNoFailures(failures, message: "Unexpected valiation failures found", file: file, line: line)
  assertNoFailures(unmatchedXFails, message: "Unmatched expected failures", file: file, line: line)
}

fileprivate extension ChildKind {
  func hasSameType(as other: ChildKind) -> Bool {
    switch (self, other) {
    case (.node(let kind), .node(kind: let otherKind)):
      return kind == otherKind
    case (.nodeChoices(let choices, _), .nodeChoices(let otherChoices, _)):
      return choices.count == otherChoices.count && zip(choices, otherChoices).allSatisfy { $0.hasSameType(as: $1) }
    case (.collection(kind: let kind, _, _, _), .collection(kind: let otherKind, _, _, _)):
      return kind == otherKind
    case (.token(let choices, _, _), .token(let otherChoices, _, _)):
      return choices == otherChoices
    case (.node(let kind), .collection(kind: let otherKind, _, _, _)):
      return kind == otherKind
    case (.collection(kind: let kind, _, _, _), .node(let otherKind)):
      return kind == otherKind
    default:
      return false
    }
  }

  var isCollection: Bool {
    switch self {
    case .node: return false
    case .nodeChoices(let choices, _): return choices.contains(where: { $0.kind.isCollection })
    case .collection: return true
    case .token: return false
    }
  }
}

fileprivate extension Child {
  func hasSameType(as other: Child) -> Bool {
    return identifier.description == other.identifier.description && kind.hasSameType(as: other.kind)
      && isOptional == other.isOptional
  }

  func isFollowedByColonToken(in node: LayoutNode) -> Bool {
    let childIndex = node.children.firstIndex(where: { $0.identifier.description == self.identifier.description })
    guard let childIndex else {
      preconditionFailure("\(self.identifier) is not a child of \(node.kind.syntaxType)")
    }
    guard childIndex + 2 < node.children.count else {
      return false
    }
    if case .token(choices: [.token(.colon)], _, _) = node.children[childIndex + 2].kind {
      return true
    } else {
      return false
    }
  }
}

fileprivate extension Array where Element: Hashable, Element: Comparable {
  /// Returns the element that occurs most frequently in the array.
  ///
  /// If there is a tie, returns the lexicographically first element.
  ///
  /// Returns `nil` if the array is empty.
  var mostCommon: Element? {
    var elementCounts: [Element: Int] = [:]
    for element in self {
      elementCounts[element, default: 0] += 1
    }
    let maxCount = elementCounts.values.max()
    return elementCounts.filter({ $0.value == maxCount }).map(\.key).sorted().first
  }
}

class ValidateSyntaxNodes: XCTestCase {
  /// All nodes with base kind e.g. `ExprSyntax` should end with `ExprSyntax`.
  func testBaseKindSuffix() {
    var failures: [ValidationFailure] = []
    for node in SYNTAX_NODES where node.base != .syntaxCollection {
      if !node.kind.syntaxType.description.hasSuffix(node.base.syntaxType.description) {
        failures.append(
          ValidationFailure(
            node: node.kind,
            message:
              "has base kind '\(node.base.syntaxType)' but type name doesn’t have '\(node.base.syntaxType)' suffix"
          )
        )
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: [
        ValidationFailure(
          node: ._canImportVersionInfo,
          message: "has base kind 'ExprSyntax' but type name doesn’t have 'ExprSyntax' suffix"
        ),
        ValidationFailure(
          node: .poundSourceLocation,
          message: "has base kind 'DeclSyntax' but type name doesn’t have 'DeclSyntax' suffix"
        ),
      ]
    )
  }

  func testSyntaxCollectionsShouldEndWithList() {
    var failures: [ValidationFailure] = []

    for node in SYNTAX_NODES.compactMap(\.collectionNode) {
      if !node.kind.syntaxType.description.hasSuffix("ListSyntax") {
        failures.append(
          ValidationFailure(
            node: node.kind,
            message: "is a collection but does not end with ListSyntax"
          )
        )
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: [
        ValidationFailure(node: .unexpectedNodes, message: "is a collection but does not end with ListSyntax")
      ]
    )
  }

  /// Implementation detail of `testSingleTokenChoiceChildNaming`, validating a single child.
  ///
  /// - Returns: A failure message if validation failed, otherwise `nil`
  private func validateSingleTokenChoiceChild(child: Child, in node: LayoutNode) -> String? {
    guard case .token(choices: let tokenChoices, _, _) = child.kind, let choice = tokenChoices.only else {
      return nil
    }
    switch choice {
    case .keyword(let keyword):
      let keywordName = keyword.spec.name

      if child.isFollowedByColonToken(in: node) {
        if child.identifier.description != "\(keywordName)Label" {
          return
            "child '\(child.identifier)' has a single keyword as its only token choice and is followed by a colon. It should thus be named '\(keywordName)Label'"
        }
      } else {
        if child.identifier.description != "\(keywordName)Keyword" {
          return
            "child '\(child.identifier)' has a single keyword as its only token choice and should thus be named '\(keywordName)Keyword'"
        }
      }

    case .token(.identifier), .token(.integerLiteral), .token(.floatLiteral):
      // We allow arbitrary naming of identifiers and literals
      break
    case .token(.comma):
      if child.identifier.description != "trailingComma" && child.identifier.description != "comma" {
        return
          "child '\(child.identifier)' has a comma keyword as its only token choice and should thus be named 'comma' or 'trailingComma'"
      }
    case .token(let token):
      let expectedChildName =
        token.spec.identifier.text
        .dropSuffix("Token")
        .dropPrefix("prefix")
        .dropPrefix("infix")
        .dropPrefix("postfix")
        .dropPrefix("binary")
        .withFirstCharacterLowercased
      if child.identifier.description != expectedChildName {
        return
          "child '\(child.identifier)' has a token as its only token choice and should thus be named '\(expectedChildName)'"
      }
    }
    return nil
  }

  /// Checks standardized naming of children with a single token choice
  ///
  /// - If a child has a single keyword as its choice, it should be named `*Keyword` (e.g. `ImportKeyword`)
  /// - If it’s another token kind, name it the same as the token choice (e.g. `LeftParen`)
  func testSingleTokenChoiceChildNaming() {
    var failures: [ValidationFailure] = []
    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for child in node.children {
        if let failureMessage = validateSingleTokenChoiceChild(child: child, in: node) {
          failures.append(ValidationFailure(node: node.kind, message: failureMessage))
        }
      }
    }
    assertFailuresMatchXFails(
      failures,
      expectedFailures: [
        // MARK: Naming of 'AsyncSpecifier' and 'ThrowsSpecifier'
        // Even though these nodes only accept e.g. 'async' name them consistently with properties that accept 'async' and 'reasync'
        ValidationFailure(
          node: .accessorEffectSpecifiers,
          message:
            "child 'asyncSpecifier' has a single keyword as its only token choice and should thus be named 'asyncKeyword'"
            // To be consistent with AsyncSpecifier properties that can be both 'async' and 'reasync'
        ),
        ValidationFailure(
          node: .deinitializerEffectSpecifiers,
          message:
            "child 'asyncSpecifier' has a single keyword as its only token choice and should thus be named 'asyncKeyword'"
            // To be consistent with AsyncSpecifier properties that can be both 'async' and 'reasync'
        ),
        ValidationFailure(
          node: .typeEffectSpecifiers,
          message:
            "child 'asyncSpecifier' has a single keyword as its only token choice and should thus be named 'asyncKeyword'"
            // To be consistent with AsyncSpecifier properties that can be both 'async' and 'reasync'
        ),

        // MARK: Two tokens with same kind in a node
        // If there are two tokens of the same kind in a node, we can't follow the naming rule without conflict
        ValidationFailure(
          node: .differentiableAttributeArguments,
          message:
            "child 'kindSpecifierComma' has a comma keyword as its only token choice and should thus be named 'comma' or 'trailingComma'"
        ),
        ValidationFailure(
          node: .differentiableAttributeArguments,
          message:
            "child 'argumentsComma' has a comma keyword as its only token choice and should thus be named 'comma' or 'trailingComma'"
        ),
        ValidationFailure(
          node: .poundSourceLocationArguments,
          message: "child 'fileColon' has a token as its only token choice and should thus be named 'colon'"
            // There are two colons in the node
        ),
        ValidationFailure(
          node: .poundSourceLocationArguments,
          message: "child 'lineColon' has a token as its only token choice and should thus be named 'colon'"
        ),
        ValidationFailure(
          node: .regexLiteralExpr,
          message:
            "child 'openingPounds' has a token as its only token choice and should thus be named 'regexPoundDelimiter'"
        ),
        ValidationFailure(
          node: .regexLiteralExpr,
          message: "child 'openingSlash' has a token as its only token choice and should thus be named 'regexSlash'"
        ),
        ValidationFailure(
          node: .regexLiteralExpr,
          message: "child 'closingSlash' has a token as its only token choice and should thus be named 'regexSlash'"
            // There are the opening and closing slashes in the node
        ),
        ValidationFailure(
          node: .regexLiteralExpr,
          message:
            "child 'closingPounds' has a token as its only token choice and should thus be named 'regexPoundDelimiter'"
            // There are the opening and closing ExtendedRegexDelimiter in the node
        ),
        // We should explicitly mention token here because it’s not obvious that the end of a file is represented by a token
        ValidationFailure(
          node: .sourceFile,
          message: "child 'endOfFileToken' has a token as its only token choice and should thus be named 'endOfFile'"
        ),
        ValidationFailure(
          node: .availabilityMacroDefinitionFile,
          message: "child 'endOfFileToken' has a token as its only token choice and should thus be named 'endOfFile'"
        ),
        ValidationFailure(
          node: .accessorBlockFile,
          message: "child 'endOfFileToken' has a token as its only token choice and should thus be named 'endOfFile'"
        ),
        ValidationFailure(
          node: .attributeClauseFile,
          message: "child 'endOfFileToken' has a token as its only token choice and should thus be named 'endOfFile'"
        ),
        ValidationFailure(
          node: .codeBlockFile,
          message: "child 'endOfFileToken' has a token as its only token choice and should thus be named 'endOfFile'"
        ),
        ValidationFailure(
          node: .memberBlockItemListFile,
          message: "child 'endOfFileToken' has a token as its only token choice and should thus be named 'endOfFile'"
        ),
        ValidationFailure(
          node: .stringLiteralExpr,
          message:
            "child 'openingPounds' has a token as its only token choice and should thus be named 'rawStringPoundDelimiter'"
        ),
        ValidationFailure(
          node: .stringLiteralExpr,
          message:
            "child 'closingPounds' has a token as its only token choice and should thus be named 'rawStringPoundDelimiter'"
        ),
        ValidationFailure(
          node: .expressionSegment,
          message:
            "child 'pounds' has a token as its only token choice and should thus be named 'rawStringPoundDelimiter'"
        ),

        // MARK: Tokens that contain underscores
        ValidationFailure(
          node: .conventionWitnessMethodAttributeArguments,
          message:
            "child 'witnessMethodLabel' has a single keyword as its only token choice and is followed by a colon. It should thus be named 'witness_methodLabel'"
            // Witness_method has an underscore and thus WitnessMethod is the correct spelling
        ),

        // MARK: Repeat node type name
        // If the node is named the same as the token, we don't need to repeat the entire token name
        ValidationFailure(
          node: .regexLiteralExpr,
          message: "child 'regex' has a token as its only token choice and should thus be named 'regexLiteralPattern'"
            // No point repeating the `Literal` because the node name alredy contains it
        ),
        ValidationFailure(
          node: .stringSegment,
          message: "child 'content' has a token as its only token choice and should thus be named 'stringSegment'"
            // The node is already named `StringSegment`
        ),

        // MARK: Miscellaneous
        // This is the only place where we use LeadingComma, similar to 'TrailingComma'
        ValidationFailure(
          node: .designatedType,
          message:
            "child 'leadingComma' has a comma keyword as its only token choice and should thus be named 'comma' or 'trailingComma'"
        ),
        // This is similar to `TrailingComma`
        ValidationFailure(
          node: .importPathComponent,
          message: "child 'trailingPeriod' has a token as its only token choice and should thus be named 'period'"
        ),
        // `~` is the only operator that’s allowed here
        ValidationFailure(
          node: .suppressedType,
          message: "child 'withoutTilde' has a token as its only token choice and should thus be named 'operator'"
        ),
        // default is not a function argument label here but a proper keyword
        ValidationFailure(
          node: .switchDefaultLabel,
          message:
            "child 'defaultKeyword' has a single keyword as its only token choice and is followed by a colon. It should thus be named 'defaultLabel'"
        ),
      ]
    )
  }

  /// If a token only has keyword token choices, its name should end with `Keyword`.
  func testMultipleKeywordChoicesNaming() {
    var failures: [ValidationFailure] = []
    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for child in node.children {
        guard case .token(choices: let tokenChoices, _, _) = child.kind,
          tokenChoices.count > 1,
          tokenChoices.allSatisfy({ $0.isKeyword })
        else {
          // Not a child with only keyword choices
          // Single token choices are handled by `validateSingleTokenChoiceChildNaming`
          continue
        }
        var failureMessage: String?
        if child.isFollowedByColonToken(in: node) {
          if child.identifier.description != "label" && !child.identifier.description.hasSuffix("Label") {
            failureMessage =
              "child '\(child.identifier)' only has keywords as its token choices, is followed by a colon and should thus end with 'Label'"
          }
        } else {
          if child.identifier.description != "specifier" && !child.identifier.description.hasSuffix("Specifier") {
            failureMessage =
              "child '\(child.identifier)' only has keywords as its token choices and should thus end with 'Specifier'"
          }
        }
        if let failureMessage {
          failures.append(ValidationFailure(node: node.kind, message: failureMessage))
        }
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: [
        // MARK: Only one non-deprecated keyword
        ValidationFailure(
          node: .consumeExpr,
          message: "child 'consumeKeyword' only has keywords as its token choices and should thus end with 'Specifier'"
            // ConsumeKeyword can be 'consume' or '_move' and '_move' is deprecated
        ),
        ValidationFailure(
          node: .borrowExpr,
          message: "child 'borrowKeyword' only has keywords as its token choices and should thus end with 'Specifier'"
            // BorrowKeyword can be 'borrow' or '_borrow', eventually '_borrow' will be deprecated
        ),
        // MARK: Conceptually a value, not a specifier
        ValidationFailure(
          node: .booleanLiteralExpr,
          message: "child 'literal' only has keywords as its token choices and should thus end with 'Specifier'"
            // TrueOrFalseKeyword would be a stupid name here
        ),
        ValidationFailure(
          node: .precedenceGroupAssignment,
          message: "child 'value' only has keywords as its token choices and should thus end with 'Specifier'"
        ),
        ValidationFailure(
          node: .precedenceGroupAssociativity,
          message: "child 'value' only has keywords as its token choices and should thus end with 'Specifier'"
        ),

        // MARK: Miscellaneous
        // 'weak' or 'unowned' are already the specifier, this is the detail in parens
        ValidationFailure(
          node: .closureCaptureSpecifier,
          message: "child 'detail' only has keywords as its token choices and should thus end with 'Specifier'"
        ),
        // This really is the modifier name and not a specifier
        ValidationFailure(
          node: .declModifier,
          message: "child 'name' only has keywords as its token choices and should thus end with 'Specifier'"
        ),
      ]
    )
  }

  /// Check that children that have the same type also have the same child name.
  func testConsistentNamingOfChildren() {
    var failures: [ValidationFailure] = []

    var childrenByNodeKind: [SyntaxNodeKind: [(node: LayoutNode, child: Child)]] = [:]

    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for child in node.children {
        guard case .node(kind: let childKind) = child.kind else {
          continue
        }
        childrenByNodeKind[childKind, default: []].append((node, child))
      }
    }

    for (kind, children) in childrenByNodeKind where !kind.isBase && kind != .token && kind != .stringLiteralExpr {
      let childNames = children.map(\.child.identifier.description)
      let mostCommonChildName = childNames.mostCommon!
      let mostCommonChild = children.first(where: { $0.child.identifier.description == mostCommonChildName })!

      for (node, child) in children {
        if child.identifier.description != mostCommonChildName {
          failures.append(
            ValidationFailure(
              node: node.kind,
              message:
                "child '\(child.identifier)' is named inconsistently with '\(mostCommonChild.node.kind.syntaxType).\(mostCommonChildName)', which has the same type ('\(kind.syntaxType)')"
            )
          )
        }
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: [
        // MARK: Alternate names for InitializerClauseSyntax
        // The cases below don’t have intializers but just a syntactic element that happens to be spelled the same
        ValidationFailure(
          node: .enumCaseElement,
          message:
            "child 'rawValue' is named inconsistently with 'ClosureCaptureSyntax.initializer', which has the same type ('InitializerClauseSyntax')"
        ),
        ValidationFailure(
          node: .enumCaseParameter,
          message:
            "child 'defaultValue' is named inconsistently with 'ClosureCaptureSyntax.initializer', which has the same type ('InitializerClauseSyntax')"
        ),
        ValidationFailure(
          node: .functionParameter,
          message:
            "child 'defaultValue' is named inconsistently with 'ClosureCaptureSyntax.initializer', which has the same type ('InitializerClauseSyntax')"
        ),
        ValidationFailure(
          node: .macroDecl,
          message:
            "child 'definition' is named inconsistently with 'ClosureCaptureSyntax.initializer', which has the same type ('InitializerClauseSyntax')"
        ),
        // MARK: Miscellaneous
        ValidationFailure(
          node: .multipleTrailingClosureElement,
          message:
            "child 'closure' is named inconsistently with 'FunctionCallExprSyntax.trailingClosure', which has the same type ('ClosureExprSyntax')"
        ),
      ]
    )
  }

  func testAllNodesThatCanConformToATraitDo() {
    var failures: [ValidationFailure] = []

    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for trait in TRAITS {
        let canConformToTrait = trait.children.allSatisfy { traitChild in
          node.children.contains { nodeChild in
            traitChild.hasSameType(as: nodeChild)
          }
        }
        if canConformToTrait && !node.traits.contains(trait.traitName) {
          failures.append(
            ValidationFailure(
              node: node.kind,
              message: "could conform to trait '\(trait.traitName)' but does not"
            )
          )
        }
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: [
        ValidationFailure(node: .accessorParameters, message: "could conform to trait 'NamedDecl' but does not"),
        ValidationFailure(node: .availabilityCondition, message: "could conform to trait 'Parenthesized' but does not"),
        ValidationFailure(node: ._canImportExpr, message: "could conform to trait 'Parenthesized' but does not"),
        ValidationFailure(
          node: .differentiabilityArguments,
          message: "could conform to trait 'Parenthesized' but does not"
        ),
        ValidationFailure(node: .editorPlaceholderDecl, message: "could conform to trait 'MissingNode' but does not"),
        ValidationFailure(node: .editorPlaceholderExpr, message: "could conform to trait 'MissingNode' but does not"),
        ValidationFailure(node: .enumCaseElement, message: "could conform to trait 'NamedDecl' but does not"),
        ValidationFailure(node: .genericParameter, message: "could conform to trait 'NamedDecl' but does not"),
        ValidationFailure(node: .precedenceGroupName, message: "could conform to trait 'NamedDecl' but does not"),
        ValidationFailure(node: .primaryAssociatedType, message: "could conform to trait 'NamedDecl' but does not"),
        ValidationFailure(
          node: .yieldedExpressionsClause,
          message: "could conform to trait 'Parenthesized' but does not"
        ),
        ValidationFailure(node: .lifetimeTypeSpecifier, message: "could conform to trait 'Parenthesized' but does not"),
        ValidationFailure(node: .codeBlockFile, message: "could conform to trait 'WithCodeBlock' but does not"),
        ValidationFailure(
          node: .keyPathMethodComponent,
          message: "could conform to trait 'Parenthesized' but does not"
        ),
      ]
    )
  }

  func testChildrenShouldNeverEndWithToken() {
    var failures: [ValidationFailure] = []

    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for child in node.nonUnexpectedChildren {
        if child.identifier.description.hasSuffix("Token") {
          failures.append(
            ValidationFailure(
              node: node.kind,
              message: "child '\(child.identifier)' should not end with 'Token'"
            )
          )
        }
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: [
        // it's not obvious that the end of file is represented by a token, thus its good to highlight it in the name
        ValidationFailure(node: .sourceFile, message: "child 'endOfFileToken' should not end with 'Token'"),
        ValidationFailure(
          node: .availabilityMacroDefinitionFile,
          message: "child 'endOfFileToken' should not end with 'Token'"
        ),
        ValidationFailure(
          node: .accessorBlockFile,
          message: "child 'endOfFileToken' should not end with 'Token'"
        ),
        ValidationFailure(
          node: .attributeClauseFile,
          message: "child 'endOfFileToken' should not end with 'Token'"
        ),
        ValidationFailure(
          node: .codeBlockFile,
          message: "child 'endOfFileToken' should not end with 'Token'"
        ),
        ValidationFailure(
          node: .memberBlockItemListFile,
          message: "child 'endOfFileToken' should not end with 'Token'"
        ),
      ]
    )
  }

  func testAllCollectionChildrenAreMarkedAsSuch() {
    var failures: [ValidationFailure] = []

    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for child in node.children {
        if case .node(kind: let kind) = child.kind, SYNTAX_NODE_MAP[kind]?.collectionNode != nil {
          failures.append(
            ValidationFailure(
              node: node.kind,
              message: "child '\(child.name)' is a SyntaxCollection but child is not marked as a collection"
            )
          )
        }
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: []
    )
  }

  func testSyntaxCollectionChildrenArePlural() {
    var failures: [ValidationFailure] = []

    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for child in node.nonUnexpectedChildren where child.kind.isCollection {
        if !child.identifier.description.hasSuffix("s") {
          failures.append(
            ValidationFailure(
              node: node.kind,
              message: "child '\(child.identifier)' is a collection and should thus be named as a plural"
            )
          )
        }
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: [
        // The child is singular here, the path just consists of multiple components
        ValidationFailure(
          node: .importDecl,
          message: "child 'path' is a collection and should thus be named as a plural"
        )
      ]
    )
  }

  /// Identifier is a wonderful ambiguous term. Almost always, 'name' or something similar is more expressive
  func testNoChildContainsIdentifier() {
    var failures: [ValidationFailure] = []

    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for child in node.nonUnexpectedChildren {
        if child.identifier.description.contains("identifier")
          || child.identifier.description.contains("Identifier")
        {
          failures.append(
            ValidationFailure(
              node: node.kind,
              message: "child '\(child.identifier)' should generally not contain 'Identifier'"
            )
          )
        }
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: [
        // The identifier expr / pattern nodes do actually have a child that’s the identifier
        ValidationFailure(
          node: .identifierPattern,
          message: "child 'identifier' should generally not contain 'Identifier'"
        )
      ]
    )
  }

  func testNoAbbreviationsInChildNames() {
    var failures: [ValidationFailure] = []

    let abbreviations = ["Args", "Params"]

    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for child in node.nonUnexpectedChildren {
        if abbreviations.contains(where: { child.name.contains($0) }) {
          failures.append(
            ValidationFailure(
              node: node.kind,
              message: "child '\(child.name)' should not contain abbreviations"
            )
          )
        }
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: []
    )
  }

  func testChildrenDontEndWithNodeKind() {
    var failures: [ValidationFailure] = []

    let forbiddenSuffixes = [
      "Decl", "Declaration", "Expr", "Expression", "Pattern", "Stmt", "Statement", "Syntax", "Type",
    ]

    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for child in node.nonUnexpectedChildren {
        for forbiddenSuffix in forbiddenSuffixes {
          if child.identifier.description.hasSuffix(forbiddenSuffix)
            && child.identifier.description != forbiddenSuffix.withFirstCharacterLowercased
          {
            failures.append(
              ValidationFailure(
                node: node.kind,
                message: "child '\(child.identifier)' should not end with '\(forbiddenSuffix)'"
              )
            )
          }
        }
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: [
        // MARK: Adjective + Type
        // There’s no real better way to name these except to use an adjective followed by 'Type'
        ValidationFailure(node: .attributedType, message: "child 'baseType' should not end with 'Type'"),
        ValidationFailure(node: .conformanceRequirement, message: "child 'leftType' should not end with 'Type'"),
        ValidationFailure(node: .conformanceRequirement, message: "child 'rightType' should not end with 'Type'"),
        ValidationFailure(node: .extensionDecl, message: "child 'extendedType' should not end with 'Type'"),
        ValidationFailure(node: .genericParameter, message: "child 'inheritedType' should not end with 'Type'"),
        ValidationFailure(
          node: .implicitlyUnwrappedOptionalType,
          message: "child 'wrappedType' should not end with 'Type'"
        ),
        ValidationFailure(node: .memberType, message: "child 'baseType' should not end with 'Type'"),
        ValidationFailure(node: .metatypeType, message: "child 'baseType' should not end with 'Type'"),
        ValidationFailure(node: .optionalType, message: "child 'wrappedType' should not end with 'Type'"),
        ValidationFailure(node: .sameTypeRequirement, message: "child 'leftType' should not end with 'Type'"),
        ValidationFailure(node: .sameTypeRequirement, message: "child 'rightType' should not end with 'Type'"),
        // MARK: Adjective + Expr
        ValidationFailure(
          node: .functionCallExpr,
          message: "child 'calledExpression' should not end with 'Expression'"
        ),
        ValidationFailure(
          node: .subscriptCallExpr,
          message: "child 'calledExpression' should not end with 'Expression'"
        ),
        ValidationFailure(node: .ternaryExpr, message: "child 'thenExpression' should not end with 'Expression'"),
        ValidationFailure(node: .ternaryExpr, message: "child 'elseExpression' should not end with 'Expression'"),
        ValidationFailure(
          node: .unresolvedTernaryExpr,
          message: "child 'thenExpression' should not end with 'Expression'"
        ),
        // MARK: Other
        // Even though the repetition pattern is not a PatternSyntax, pattern is the correct term here
        ValidationFailure(node: .packExpansionExpr, message: "child 'repetitionPattern' should not end with 'Pattern'"),
        ValidationFailure(node: .packExpansionType, message: "child 'repetitionPattern' should not end with 'Pattern'"),
      ]
    )
  }

  /// Nodes ending with `List` should always be syntax collections
  func testNonCollectionNodesShouldntContainList() {
    var failures: [ValidationFailure] = []

    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      if node.kind.syntaxType.description.contains("List") {
        failures.append(
          ValidationFailure(
            node: node.kind,
            message: "non-collection node should not contain 'List'"
          )
        )
      }
    }

    assertFailuresMatchXFails(
      failures,
      expectedFailures: [
        ValidationFailure(
          node: .memberBlockItemListFile,
          message: "non-collection node should not contain 'List'"
        )
      ]
    )
  }

  /// Children should always have a plural as their name instead of ending with 'List'.
  func testChildrenDontEndWithList() {
    var failures: [ValidationFailure] = []

    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for child in node.children {
        if child.name.contains("List") {
          failures.append(
            ValidationFailure(
              node: node.kind,
              message:
                "child '\(child.name)' should not contain 'List'"
            )
          )
        }
      }
    }

    assertFailuresMatchXFails(failures, expectedFailures: [])
  }

  /// Entry is such an ambiguous term that we shouldn’t use it.
  /// There are almost always better names
  func testNoEntryInTypeNames() {
    var failures: [ValidationFailure] = []

    for node in SYNTAX_NODES {
      if node.kind.syntaxType.description.contains("Entry") {
        failures.append(
          ValidationFailure(
            node: node.kind,
            message:
              "non-collection node shouldn’t contain 'List'"
          )
        )
      }
    }

    assertFailuresMatchXFails(failures, expectedFailures: [])
  }

  func testNoOptionalSyntaxCollections() {
    var failures: [ValidationFailure] = []

    for node in SYNTAX_NODES.compactMap(\.layoutNode) {
      for child in node.children {
        if case .collection = child.kind, child.isOptional, !child.isUnexpectedNodes {
          failures.append(
            ValidationFailure(
              node: node.kind,
              message:
                "child '\(child.name)' is an optional syntax collection. All syntax collections should be non-optional."
            )
          )
        }
      }
    }

    assertFailuresMatchXFails(failures, expectedFailures: [])
  }
}