Update CompressionHandlerTests.cs

Ensure that compressed data is the same as decompressed data.

Author: George

tests/Microsoft.Graph.DotnetCore.Core.Test/Requests/Middleware/CompressionHandlerTests.cs

@@ -125,7 +125,9 @@ public async Task CompressionHandler_should_keep_headers_after_decompression()
             this.testHttpMessageHandler.SetHttpResponse(httpResponse);
 
             HttpResponseMessage compressedResponse = await this.invoker.SendAsync(httpRequestMessage, new CancellationToken());
-            string responseContentString = await compressedResponse.Content.ReadAsStringAsync();
+            string decompressedResponseString = await compressedResponse.Content.ReadAsStringAsync();
+
+            Assert.Equal(decompressedResponseString, stringToCompress);
 
             // Ensure that headers in the compressedResponse are the same as in the original, expected response.
             Assert.NotEmpty(compressedResponse.Headers);