Added tests for Write-Debug, Write-Verbose, Write-Error cmdlets

src/pester-tests/Write-Stream.Tests.ps1

@@ -0,0 +1,71 @@
+Describe "Stream writer tests" {
+    $targetfile = "writeoutput.txt"
+
+    # A custom function is defined here do handle the debug stream dealing with the confirm prompt
+    # that would normally
+    function Write-Messages
+    {
+        [CmdletBinding()]
+
+        param()
+        If ($PSBoundParameters['Debug']) { $DebugPreference = 'Continue' }
+        Write-Verbose "Verbose message"
+
+        Write-Debug "Debug message"
+
+    }
+
+    function Get-OutputResults
+    {
+        # Get the contents of the targetfile.
+        # Make the array a string for less brittle testing
+        $output = $(Get-Content $args[0])
+        [String]::Join([Environment]::NewLine, $output )
+
+        return $output
+    }
+    Context "Redirect Stream Tests" {
+    # These tests validate that a stream is actually being written to by redirecting the output of that stream
+
+        AfterEach { Remove-Item $targetfile }
+        It "Should write warnings to the warning stream" {
+            Write-Warning "Test Warning" 3>&1 > $targetfile
+
+            Get-Content $targetfile | Should Be "Test Warning"
+        }
+
+        It "Should write error messages to the error stream" {
+            Write-Error "Testing Error" 2>&1 > $targetfile
+
+            $result = Get-OutputResults $targetfile
+            # The contents of the error stream should contain the expected text
+            $result -match ": Testing Error" | Should Be $true
+        }
+
+        It "Should write debug messages to the debug stream" {
+           Write-Messages -Debug -EA SilentlyContinue 5>&1 > $targetfile
+
+            $result = Get-OutputResults $targetfile
+
+            # The contents of the debug stream should contain the expected text
+            $result -match "Debug Message" | Should Be $true
+        }
+
+        It "Should write messages to the verbose stream" {
+            Write-Messages -Verbose 4>&1 > $targetfile
+
+            $result = Get-OutputResults $targetfile
+
+            # The contents of the debug stream should contain the expected text
+            $result -match "Verbose Message" | Should Be $true
+        }
+    }
+
+    Context "Error automatic variable" {
+        It "Should write error messages to the `$Error automatic variable" {
+            Write-Error "Test Error Message" -ErrorAction SilentlyContinue
+
+            $Error[0] | Should Match "Test Error Message"
+        }
+    }
+}