public void TestFirstWhenDoesntExists()
{
var array = new int[] { 2, 5, 3 };
Func <int, bool> myFunc = (x) => { return(x == 4); };
var msg = Assert.Throws <InvalidOperationException>(() => LinqFunctions.First(array, p => myFunc(p)));
Assert.Equal("No element has been found", msg.Message);
}
public void TestFirstWhenSourceIsNull()
{
int[] array = null;
Func <int, bool> myFunc = (x) => { return(x == 4); };
var msg = Assert.Throws <ArgumentNullException>(() => LinqFunctions.First(array, p => myFunc(p)));
Assert.Equal("Value cannot be null.\r\nParameter name: source", msg.Message);
}
public void TestFirstWhenExists()
{
var array = new int[] { 1, 2, 3, 4, 5 };
Func <int, bool> myFunc = (x) => { return(x == 4); };
var result = LinqFunctions.First(array, p => myFunc(p));
Assert.Equal(4, result);
}