.NET Dictionaries have same keys and values, but aren't “equal”

Question

This test fails:

using Microsoft.VisualStudio.TestTools.UnitTesting;        

[TestMethod()]
        public void dictEqualTest() {
            IDictionary<         


        

Answer 1

If you are specifically interested in how you can fix this from unit testing perspective:

Try this

CollectionAssert.AreEquivalent(dict.ToList(), dictClone.ToList());

Explanation

There are extension methods on IDictionary - such as .ToList() - available in .Net 3.5 and up, which will convert the dictionary into a collection of KeyValuePair that can be easily compared with CollectionAssert.AreEquivalent.

They'll even give reasonably helpful error messages! Example usage:

IDictionary d1 = new Dictionary {
    { "a", "1"}, {"b", "2"}, {"c", "3"}};

IDictionary d2 = new Dictionary {
    {"b", "2"}, { "a", "1"}, {"c", "3"}}; // same key-values, different order

IDictionary d3 = new Dictionary {
    { "a", "1"}, {"d", "2"}, {"c", "3"}}; // key of the second element differs from d1

IDictionary d4 = new Dictionary {
    { "a", "1"}, {"b", "4"}, {"c", "3"}}; // value of the second element differs from d1

CollectionAssert.AreEquivalent(d1.ToList(), d2.ToList());
//CollectionAssert.AreEquivalent(d1.ToList(), d3.ToList()); // fails!
//CollectionAssert.AreEquivalent(d1.ToList(), d4.ToList()); // fails!

// if uncommented, the 2 tests above fail with error:
//   CollectionAssert.AreEquivalent failed. The expected collection contains 1
//   occurrence(s) of <[b, 2]>. The actual collection contains 0 occurrence(s).