Add support for Flexbuffers in wasm (#8815)

tests/swift/Wasm.tests/Tests/FlexBuffers.Test.Swift.WasmTests/FlexBuffersStringTests.swift

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2024 Google Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import Common
+import FlexBuffers
+import XCTest
+
+final class FlexBuffersStringTests: XCTestCase {
+
+  func testEncodingUnicodeString() {
+    let text = "プ画をみて✋"
+
+    let bytes = text.data(using: .unicode, allowLossyConversion: true)
+    var flx = FlexBuffersWriter()
+    flx.map { writer in
+      writer.add(blob: bytes!, key: "text", length: bytes!.count)
+    }
+    flx.finish()
+    let byteBuffer = flx.sizedByteBuffer
+
+    let reference = try! getRoot(buffer: byteBuffer)
+    let root = reference?.map?["text"]
+    let builtString = root?.blob {
+      let data = Data(bytes: $0.baseAddress!, count: Int($0.count))
+      return String(data: data, encoding: .unicode)
+    }
+
+    XCTAssertEqual(builtString, text)
+  }
+}