Adds Swift/C++ interoperality test for struct

The struct object in question contains a std::string property whose type
does not support direct conversion in Swift. Test case verifies that
Swift could still modify this property as long as it does not have to
initialize the value to be assigned. Also, the object with such property
could be passed into other C++ functions to be read and modified.

Bug: N/A
Change-Id: I16ed68f6e934b8abd21142ecb7467f25ee94d989
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4261808
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Stepan Khapugin <stkhapugin@chromium.org>
Auto-Submit: Ginny Huang <ginnyhuang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1106720}

ios/chrome/test/swift_interop/BUILD.gn

@@ -31,6 +31,7 @@ source_set("swift_interop_tests_support_files") {
     "pointer/pointer_returner.h",
     "pointer/unique_ptr.cc",
     "pointer/unique_ptr.h",
+    "struct/struct.h",
   ]
 }
 
@@ -47,6 +48,7 @@ swift_source_set("swift_interop_tests") {
     "pointer/object_passing_xctest.swift",
     "pointer/pointer_xctest.swift",
     "pointer/unique_ptr_xctest.swift",
+    "struct/struct_xctest.swift",
   ]
   frameworks = [ "UIKit.framework" ]
   deps = [

ios/chrome/test/swift_interop/module.modulemap

@@ -32,3 +32,7 @@ module Pointer {
   requires cplusplus
 }
 
+module Struct {
+  header "struct/struct.h"
+  requires cplusplus
+}

ios/chrome/test/swift_interop/struct/struct.h

@@ -0,0 +1,26 @@
+// Copyright 2023 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef IOS_CHROME_TEST_SWIFT_INTEROP_STRUCT_STRUCT_H_
+#define IOS_CHROME_TEST_SWIFT_INTEROP_STRUCT_STRUCT_H_
+
+#include <string>
+
+// Boolean, but for foo.
+struct Foolean {
+  Foolean() {}
+
+  bool value;
+  std::string description;
+
+  static std::string GetDescriptionForValue(bool value) {
+    return std::string(value ? "true" : "false");
+  }
+};
+
+inline bool IsFooleanValid(Foolean foo) {
+  return foo.description == Foolean::GetDescriptionForValue(foo.value);
+}
+
+#endif  // IOS_CHROME_TEST_SWIFT_INTEROP_STRUCT_STRUCT_H_

ios/chrome/test/swift_interop/struct/struct_xctest.swift

@@ -0,0 +1,25 @@
+// Copyright 2023 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import Struct
+import XCTest
+
+class StructTest: XCTestCase {
+
+  func testStruct() throws {
+    var goodFoo = Foolean()
+    var badFoo = Foolean()
+
+    // Test calling static method from struct.
+    goodFoo.value = true
+    goodFoo.description = Foolean.GetDescriptionForValue(true)
+    badFoo.value = false
+    badFoo.description = Foolean.GetDescriptionForValue(true)
+
+    // Test passing object defined in C++ and initialized in Swift to top level C++ functions.
+    XCTAssertTrue(IsFooleanValid(goodFoo))
+    XCTAssertFalse(IsFooleanValid(badFoo))
+  }
+
+}