Describe

Defines the context bounds of a test. One may use this block to encapsulate a scenario for testing - a set of conditions assumed to be present and that should lead to various expected results represented by the It blocks.

PARAMETERS

###Name The name of the Test. This is often an expressive phrase describing the scenario being tested.

###Fixture The actual test script. If you are following the AAA pattern (Arrange-Act-Assert), this typically holds the arrange and act sections. The Asserts will also lie in this block but are typically nested each in its own It block. Assertions are typically performed by the Should command within the It blocks.

###Tags Optional parameter containing an array of strings. When calling Invoke-Pester, it is possible to specify a -Tag parameter which will only execute Describe blocks containing the same Tag.

EXAMPLE

function Add-Numbers($a, $b) {
    return $a + $b
}

Describe "Add-Numbers" {
    It "adds positive numbers" {
        $sum = Add-Numbers 2 3
        $sum | Should Be 5
    }

    It "adds negative numbers" {
        $sum = Add-Numbers (-2) (-2)
        $sum | Should Be (-4)
    }

    It "adds one negative number to positive number" {
        $sum = Add-Numbers (-2) 2
        $sum | Should Be 0
    }

    It "concatenates strings if given strings" {
        $sum = Add-Numbers two three
        $sum | Should Be "twothree"
    }
}