/// <summary>
/// Tests the difference between to enumerations.
/// </summary>
/// <typeparam name="T">The item type</typeparam>
/// <param name="a">The 'A' collection.</param>
/// <param name="b">The 'B' collection.</param>
/// <param name="expectedResult">The expected result.</param>
/// <param name="comparer">The optional equality comparer for the <typeparamref name="T"/> type.</param>
private static void TestDiff <T>(
[NotNull] IReadOnlyList <T> a,
[NotNull] IReadOnlyList <T> b,
[NotNull] DiffResult <T> expectedResult,
IEqualityComparer <T> comparer = null)
{
if (comparer == null)
{
comparer = EqualityComparer <T> .Default;
}
Assert.IsNotNull(a, "The 'A' collection cannot be null.");
Assert.IsNotNull(b, "The 'B' collection cannot be null.");
Assert.IsNotNull(expectedResult, "The expected result cannot be null.");
Tuple <bool, IEnumerable <T>, IEnumerable <T> >[] er = expectedResult.ToArray();
CollectionAssert.AllItemsAreNotNull(er, "Expected result contains null.");
Differences <T> actualResult = a.Diff(b, comparer);
Assert.IsNotNull(actualResult, "The diff operation returned null.");
Chunk <T>[] ar = actualResult.ToArray();
CollectionAssert.AllItemsAreNotNull(ar, "Actual result contains null.");
Trace.WriteLine($"Chunks:\r\n{actualResult}");
Assert.AreEqual(er.Length, ar.Length, $"{ar.Length} actual results returned instead of the expected {er.Length}.");
for (int i = 0; i < er.Length; i++)
{
Tuple <bool, IEnumerable <T>, IEnumerable <T> > eri = er[i];
Chunk <T> ari = ar[i];
Assert.IsNotNull(ari, $"The actual chunk of the #{i} difference was null.");
Assert.AreEqual(eri.Item1, ari.AreEqual, $"The actual chunk of the #{i} difference was {(ari.AreEqual ? "equal" : "not equal")}, when the expected result was {(eri.Item1 ? "equal" : "not equal")}.");
if (ari.A == null)
{
Assert.IsNull(
eri.Item2,
$"The actual chunk A of the #{i} difference was null, when the expected chunk A is not null.");
}
else
{
Assert.IsNotNull(
eri.Item2,
$"The actual chunk A of the #{i} difference was not null, when the expected chunk A is null.");
IEnumerator <T> eriae = eri.Item2.GetEnumerator();
IEnumerator <T> ariae = ari.A.GetEnumerator();
int j = 0;
while (eriae.MoveNext())
{
Assert.IsTrue(
ariae.MoveNext(),
$"The actual chunk A of the #{i} difference only had {j} items, whilst more were expected.");
Assert.IsTrue(
comparer.Equals(eriae.Current, ariae.Current),
$"The #{j} item '{ariae.Current}' of the A #{i} difference did not match the expected item '{eriae.Current}'.");
j++;
}
Assert.IsFalse(
ariae.MoveNext(),
$"The actual chunk A of the #{i} difference has more than the {j} expected items.");
}
if (ari.B == null)
{
Assert.IsNull(
eri.Item3,
$"The actual chunk B of the #{i} difference was null, when the expected chunk B is not null.");
}
else
{
Assert.IsNotNull(
eri.Item3,
$"The actual chunk B of the #{i} difference was not null, when the expected chunk B is null.");
IEnumerator <T> eribe = eri.Item3.GetEnumerator();
IEnumerator <T> aribe = ari.B.GetEnumerator();
int j = 0;
while (eribe.MoveNext())
{
Assert.IsTrue(
aribe.MoveNext(),
$"The actual chunk B of the #{i} difference only had {j} items, whilst more were expected.");
Assert.IsTrue(
comparer.Equals(eribe.Current, aribe.Current),
$"The #{j} item '{aribe.Current}' of the B #{i} difference did not match the expected item '{eribe.Current}'.");
j++;
}
Assert.IsFalse(
aribe.MoveNext(),
$"The actual chunk B of the #{i} difference has more than the {j} expected items.");
}
}
}