public void AddWorksLikeSetAndThrowsIfKeyExists()
{
IDictionary <string, StringValues> headers = new FrameRequestHeaders();
StringValues value;
Assert.False(headers.TryGetValue("host", out value));
Assert.False(headers.TryGetValue("custom", out value));
Assert.False(headers.TryGetValue("Content-Length", out value));
headers.Add("host", new[] { "localhost" });
headers.Add("custom", new[] { "value" });
headers.Add("Content-Length", new[] { "0" });
Assert.True(headers.TryGetValue("host", out value));
Assert.True(headers.TryGetValue("custom", out value));
Assert.True(headers.TryGetValue("Content-Length", out value));
Assert.Throws <ArgumentException>(() => headers.Add("host", new[] { "localhost" }));
Assert.Throws <ArgumentException>(() => headers.Add("custom", new[] { "value" }));
Assert.Throws <ArgumentException>(() => headers.Add("Content-Length", new[] { "0" }));
Assert.True(headers.TryGetValue("host", out value));
Assert.True(headers.TryGetValue("custom", out value));
Assert.True(headers.TryGetValue("Content-Length", out value));
}
