added set-alias tests

src/pester-tests/Set-Alias.Tests.ps1

@@ -0,0 +1,23 @@
+Describe "Set-Alias" {
+    Mock Get-Date { return "Friday, October 30, 2015 3:38:08 PM" }
+    It "Should be able to set alias without error" {
+
+        { set-alias -Name gd -Value Get-Date } | Should Not Throw
+    }
+
+    It "Should be able to have the same output between set-alias and the output of the function being aliased" {
+        gd | Should Be $(Get-Date)
+    }
+
+    It "Should be able to use the sal alias" {
+        { sal gd Get-Date } | Should Not Throw
+    }
+
+    It "Should have the same output between the sal alias and the original set-alias cmdlet" {
+        sal -Name gd -Value Get-Date
+
+        Set-Alias -Name gd2 -Value Get-Date
+
+        gd2 | Should Be $(gd)
+    }
+}