ToXUnitAssertion(): verbosely assert a dictionary's contents

DictionaryExtensions.ToXUnitAssertion.cs

public static class DictionaryExtensions
{
    public static string ToXUnitAssertion<TKey, TValue>([NotNull] this IDictionary<TKey, TValue> dictionary, string variableName = "dictionary")
    {
        var isKeyString = typeof(TKey) == typeof(string);
        var isValueString = typeof(TValue) == typeof(string);
        string GetKey(TKey key) => isKeyString ? $"\"{key}\"" : key.ToString();
        string GetValue(TValue value) => isValueString ? $"\"{value}\"" : value.ToString();

        var stringBuilder = new StringBuilder();
        stringBuilder.Append($"Assert.Equal({dictionary.Count}, {variableName}.Count); ");

        foreach (var keyValuePair in dictionary)
        {
            stringBuilder.Append($"Assert.True({variableName}.ContainsKey({GetKey(keyValuePair.Key)})); ");
            stringBuilder.Append($"Assert.Equal({GetValue(dictionary[keyValuePair.Key])}, {variableName}[{GetKey(keyValuePair.Key)}]); ");
        }

        return stringBuilder.ToString();
    }
}