Refactor AttributeRemover to remove attributes matching a predicate

Updated `MacroApplication` and `AttributeRemoverTests` to the new
predicate-based `AttributeRemover` usage.

Author: gohanlon

Sources/SwiftSyntaxMacroExpansion/MacroSystem.swift

@@ -386,23 +386,18 @@ struct MacroSystem {
 /// Removes attributes from a syntax tree while maintaining their surrounding trivia.
 @_spi(Testing)
 public class AttributeRemover: SyntaxRewriter {
-  var attributesToRemove: [AttributeSyntax]
-  let attributeEquals: (AttributeSyntax, AttributeSyntax) -> Bool
+  let predicate: (AttributeSyntax) -> Bool
 
   var triviaToAttachToNextToken: Trivia = Trivia()
 
-  public init(
-    attributesToRemove: [AttributeSyntax],
-    attributeEquals: @escaping (AttributeSyntax, AttributeSyntax) -> Bool = { $0 == $1 }
-  ) {
-    self.attributesToRemove = attributesToRemove
-    self.attributeEquals = attributeEquals
+  public init(where predicate: @escaping (AttributeSyntax) -> Bool) {
+    self.predicate = predicate
   }
 
   public override func visit(_ node: AttributeListSyntax) -> AttributeListSyntax {
     var filteredAttributes: [AttributeListSyntax.Element] = []
     for case .attribute(let attribute) in node {
-      if attributesToRemove.contains(where: { self.attributeEquals($0, attribute) }) {
+      if self.predicate(attribute) {
         var leadingTrivia = attribute.leadingTrivia
 
         // Don't leave behind an empty line when the attribute being removed is on its own line,
@@ -579,7 +574,7 @@ private class MacroApplication<Context: MacroExpansionContext>: SyntaxRewriter {
 
       let attributesToRemove = self.macroAttributes(attachedTo: visitedNode).map(\.attributeNode)
 
-      return AttributeRemover(attributesToRemove: attributesToRemove).rewrite(visitedNode)
+      return AttributeRemover(where: { attributesToRemove.contains($0) }).rewrite(visitedNode)
     }
 
     return nil

Tests/SwiftSyntaxMacroExpansionTest/AttributeRemoverTests.swift

@@ -22,11 +22,10 @@ fileprivate func assertSyntaxRemovingTestAttributes(
   file: StaticString = #filePath,
   line: UInt = #line
 ) {
-  let attributesToRemove = ["@Test"].map(AttributeSyntax.init(stringLiteral:))
+  let attributeToRemove = AttributeSyntax(stringLiteral: "@Test")
 
   let reducedSource = AttributeRemover(
-    attributesToRemove: attributesToRemove,
-    attributeEquals: { $0.trimmedDescription == $1.trimmedDescription }
+    where: { $0.trimmedDescription == attributeToRemove.trimmedDescription }
   )
   .rewrite(
     Parser.parse(source: originalSource)