public void TestComparerEquality()
{
Func <int, int> f = i => - i;
TestEquality(Comparers.Create(f), Comparers.Create(f), Comparers.Create((int i) => i.ToString()));
TestEquality(Comparers.Reverse <int>(), Comparers.Reverse <int>(), Comparers.Create((int i) => i.ToString()).Reverse());
var first = Comparers.Create((string s) => s.Length);
var second = Comparers.Create((string s) => s[0]);
TestEquality(first.ThenBy(second), first.ThenBy(second), second.ThenBy(first));
TestEquality(Comparers.GetSequenceComparer <string>(), Comparers.GetSequenceComparer(Comparer <string> .Default), Comparers.GetSequenceComparer(StringComparer.OrdinalIgnoreCase));
}
public void TestReverse()
{
Enumerable.Range(0, 5).OrderBy(i => i, Comparers.Reverse <int>())
.SequenceShouldEqual(new[] { 4, 3, 2, 1, 0 });
Assert.Same(Comparers.Reverse <int>(), Comparers.Reverse <int>());
Assert.Same(Comparers.Reverse <int>(), Comparer <int> .Default.Reverse());
var backwardsStringComparer = Comparer <string> .Create((s1, s2) => string.CompareOrdinal(string.Join(string.Empty, s1.Reverse()), string.Join(string.Empty, s2.Reverse())));
var reverseBackwardsStringComparer = backwardsStringComparer.Reverse();
new[] { "abc", "cab", "bac" }.OrderBy(s => s, reverseBackwardsStringComparer)
.SequenceShouldEqual(new[] { "abc", "bac", "cab" });
Assert.Throws <ArgumentNullException>(() => reverseBackwardsStringComparer.Compare("a", null));
Math.Sign(Comparer <int?> .Default.Reverse().Compare(1, null)).ShouldEqual(-1);
}
public void TestMinByAndMaxBy()
{
Assert.Throws <ArgumentNullException>(() => default(IEnumerable <object>).MinBy(x => 2));
Assert.Throws <ArgumentNullException>(() => default(IEnumerable <object>).MaxBy(x => 2));
Assert.Throws <ArgumentNullException>(() => new[] { 1 }.MinBy(default(Func <int, int>)));
Assert.Throws <ArgumentNullException>(() => new[] { 1 }.MaxBy(default(Func <int, int>)));
Assert.Throws <InvalidOperationException>(() => new int[0].MinBy(i => "a"));
Assert.Throws <InvalidOperationException>(() => new int[0].MaxBy(i => "a"));
new int?[0].MinBy(i => "a").ShouldEqual(null);
new int?[0].MaxBy(i => "a").ShouldEqual(null);
new string[0].MinBy(i => 1).ShouldEqual(null);
new string[0].MaxBy(i => 1).ShouldEqual(null);
new[] { "z", "aa", }.MinBy(s => s.Length).ShouldEqual("z");
new[] { "z", "aa" }.MaxBy(s => s.Length).ShouldEqual("aa");
new[] { default(int?), 1, default(int?) }.MinBy(i => i).ShouldEqual(1);
new[] { default(int?), 1, default(int?) }.MaxBy(i => i).ShouldEqual(1);
new[] { 1, 2, 3, 2, 1 }.MinBy(i => 2 * i, Comparers.Reverse <int>()).ShouldEqual(3);
new[] { 3, 2, 1, 2, 3 }.MaxBy(i => 2 * i, Comparers.Reverse <int>()).ShouldEqual(1);
}