Add symbol name unit tests

Tests/SwiftSyntaxTest/SymbolNameTests.swift

@@ -0,0 +1,207 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2024 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 SwiftSyntax
+import XCTest
+
+final class SymbolNameTests: XCTestCase {
+
+  // MARK: - Functions
+
+  func testFunctionNameWithoutParameters() {
+    assertSymbolName(ofFunction: "func name() {}", expecting: "name()")
+  }
+
+  func testFunctionNameWithSingleNamedParameter() {
+    assertSymbolName(ofFunction: "func name(one: Int) {}", expecting: "name(one:)")
+  }
+
+  func testFunctionNameWithSingleUnnamedParameter() {
+    assertSymbolName(ofFunction: "func name(_: Int) {}", expecting: "name(_:)")
+  }
+
+  func testFunctionNameWithExternalParameterName() {
+    assertSymbolName(ofFunction: "func name(one two: Int) {}", expecting: "name(one:)")
+  }
+
+  func testFunctionNameWithExplicitExternalParameterName() {
+    assertSymbolName(ofFunction: "func name(one _: Int) {}", expecting: "name(one:)")
+  }
+
+  func testFunctionNameWithImplicitExternalParameterName() {
+    assertSymbolName(ofFunction: "func name(_ two: Int) {}", expecting: "name(_:)")
+  }
+
+  func testFunctionNameWithOnlyAnonymousParameters() {
+    assertSymbolName(ofFunction: "func name(_ _: Int) {}", expecting: "name(_:)")
+  }
+
+  func testFunctionNameWithMultipleNamedParameters() {
+    assertSymbolName(ofFunction: "func name(one two: Int, three: Int) {}", expecting: "name(one:three:)")
+  }
+
+  func testFunctionNameWithAllParametersHavingExternalNames() {
+    assertSymbolName(ofFunction: "func name(one two: Int, three four: Int) {}", expecting: "name(one:three:)")
+  }
+
+  func testFunctionNameWithMixedNamedAndAnonymousParameters() {
+    assertSymbolName(ofFunction: "func name(one two: Int, _ four: Int) {}", expecting: "name(one:_:)")
+  }
+
+  func testFunctionNameWithAllAnonymousParameters() {
+    assertSymbolName(ofFunction: "func name(_ two: Int, _ four: Int) {}", expecting: "name(_:_:)")
+  }
+
+  func testFunctionNameWithBackticks() {
+    assertSymbolName(ofFunction: "func `name`() {}", expecting: "name()")
+  }
+
+  func testFunctionNameWithParameterNameInBackticks() {
+    assertSymbolName(ofFunction: "func name(`one`: Int) {}", expecting: "name(one:)")
+  }
+
+  // FIXME: Does this make sense?
+  func testOperatorFunctionName() {
+    assertSymbolName(ofFunction: "func == (one: Int, two: Int)", expecting: "==(one:two:)")
+  }
+
+  private func assertSymbolName(
+    ofFunction function: DeclSyntax,
+    expecting expectedSymbolName: String,
+    file: StaticString = #filePath,
+    line: UInt = #line
+  ) {
+    guard let functionDecl = function.as(FunctionDeclSyntax.self) else {
+      XCTFail("Expected function declaration not found.", file: file, line: line)
+      return
+    }
+
+    XCTAssertEqual(functionDecl.symbolName, expectedSymbolName, file: file, line: line)
+  }
+
+  // MARK: - Initializer
+
+  func testInitializerWithoutParameters() {
+    assertSymbolName(ofInitializer: "init() {}", expecting: "init()")
+  }
+
+  func testInitializerWithSingleNamedParameter() {
+    assertSymbolName(ofInitializer: "init(one: Int) {}", expecting: "init(one:)")
+  }
+
+  func testInitializerWithSingleUnnamedParameter() {
+    assertSymbolName(ofInitializer: "init(_: Int) {}", expecting: "init(_:)")
+  }
+
+  func testInitializerWithExternalParameterName() {
+    assertSymbolName(ofInitializer: "init(one two: Int) {}", expecting: "init(one:)")
+  }
+
+  func testInitializerWithExplicitExternalParameterName() {
+    assertSymbolName(ofInitializer: "init(one _: Int) {}", expecting: "init(one:)")
+  }
+
+  func testInitializerWithImplicitExternalParameterName() {
+    assertSymbolName(ofInitializer: "init(_ two: Int) {}", expecting: "init(_:)")
+  }
+
+  func testInitializerWithOnlyAnonymousParameters() {
+    assertSymbolName(ofInitializer: "init(_ _: Int) {}", expecting: "init(_:)")
+  }
+
+  func testInitializerWithMultipleNamedParameters() {
+    assertSymbolName(ofInitializer: "init(one two: Int, three: Int) {}", expecting: "init(one:three:)")
+  }
+
+  func testInitializerWithAllParametersHavingExternalNames() {
+    assertSymbolName(ofInitializer: "init(one two: Int, three four: Int) {}", expecting: "init(one:three:)")
+  }
+
+  func testInitializerWithMixedNamedAndAnonymousParameters() {
+    assertSymbolName(ofInitializer: "init(one two: Int, _ four: Int) {}", expecting: "init(one:_:)")
+  }
+
+  func testInitializerWithAllAnonymousParameters() {
+    assertSymbolName(ofInitializer: "init(_ two: Int, _ four: Int) {}", expecting: "init(_:_:)")
+  }
+
+  func testInitializerWithNameInBackticks() {
+    assertSymbolName(ofInitializer: "init(`one`: Int) {}", expecting: "init(one:)")
+  }
+
+  private func assertSymbolName(
+    ofInitializer initializer: DeclSyntax,
+    expecting expectedSymbolName: String,
+    file: StaticString = #filePath,
+    line: UInt = #line
+  ) {
+    guard let initializerDecl = initializer.as(InitializerDeclSyntax.self) else {
+      XCTFail("Expected initializer declaration not found.", file: file, line: line)
+      return
+    }
+
+    XCTAssertEqual(initializerDecl.symbolName, expectedSymbolName, file: file, line: line)
+  }
+
+  // MARK: - Subscript
+
+  func testSubscriptWithoutParameters() {
+    assertSymbolName(ofSubscript: "subscript() -> Int { 0 }", expecting: "subscript()")
+  }
+
+  func testSubscriptWithSingleParameter() {
+    assertSymbolName(ofSubscript: "subscript(index: Int) -> Int { 0 }", expecting: "subscript(_:)")
+  }
+
+  func testSubscriptWithExternalParameterNames() {
+    assertSymbolName(ofSubscript: "subscript(index i: Int) -> Int { 0 }", expecting: "subscript(index:)")
+  }
+
+  func testSubscriptWithUnnamedParameter() {
+    assertSymbolName(ofSubscript: "subscript(_ index: Int) -> Int { 0 }", expecting: "subscript(_:)")
+  }
+
+  func testSubscriptWithUnnamedParameter_2() {
+    assertSymbolName(ofSubscript: "subscript(_ i: Int) -> Int { 0 }", expecting: "subscript(_:)")
+  }
+
+
+  func testSubscriptWithOnlyAnonymousParameters() {
+    assertSymbolName(ofSubscript: "subscript(_ _: Int) -> Int { 0 }", expecting: "subscript(_:)")
+  }
+
+  func testSubscriptWithMultipleParameters() {
+    assertSymbolName(ofSubscript: "subscript(x: Int, y: Int) -> Int { 0 }", expecting: "subscript(_:_:)")
+  }
+
+  func testSubscriptWithMultipleParameters2() {
+    assertSymbolName(ofSubscript: "subscript(indexX x: Int, indexY y: Int) -> Int { 0 }", expecting: "subscript(indexX:indexY:)")
+  }
+
+  func testSubscriptWithParameterNameInBackticks() {
+      assertSymbolName(ofSubscript: "subscript(`index` i: Int) -> Int { 0 }", expecting: "subscript(index:)")
+  }
+
+  private func assertSymbolName(
+    ofSubscript subscriptDeclaration: DeclSyntax,
+    expecting expectedSymbolName: String,
+    file: StaticString = #filePath,
+    line: UInt = #line
+  ) {
+    guard let subscriptDecl = subscriptDeclaration.as(SubscriptDeclSyntax.self) else {
+      XCTFail("Expected subscript declaration not found.", file: file, line: line)
+      return
+    }
+
+    XCTAssertEqual(subscriptDecl.symbolName, expectedSymbolName, file: file, line: line)
+  }
+}