Add additional tests for Clear-Content to improve coverage (#3157)

Coverage has improved to more than 85% for Clear-Content

test/powershell/Modules/Microsoft.PowerShell.Management/Clear-Content.Tests.ps1

@@ -1,26 +1,175 @@
+# get a random string of characters a-z and A-Z
+function Get-RandomString
+{
+    param ( [int]$length = 8 )
+    $chars = .{ ([int][char]'a')..([int][char]'z');([int][char]'A')..([int][char]'Z') }
+    ([char[]]($chars | get-random -count $length)) -join ""
+}
+
+# get a random string which is not the name of an existing provider
+function Get-NonExistantProviderName
+{
+   param ( [int]$length = 8 )
+   do {
+       $providerName = get-randomstring -length $length
+   } until ( (get-psprovider -PSProvider $providername -erroraction silentlycontinue) -eq $null )
+   $providerName
+}
+
+# get a random string which is not the name of an existing drive
+function Get-NonExistantDriveName
+{
+    param ( [int]$length = 8 )
+    do {
+        $driveName = Get-RandomString -length $length
+    } until ( (get-psdrive $driveName -erroraction silentlycontinue) -eq $null )
+    $drivename
+}
+
+# get a random string which is not the name of an existing function
+function Get-NonExistantFunctionName
+{
+    param ( [int]$length = 8 )
+    do {
+        $functionName = Get-RandomString -length $length
+    } until ( (test-path function:$functionName) -eq $false )
+    $functionName
+}
+
 Describe "Clear-Content cmdlet tests" -Tags "CI" {
+  BeforeAll {
     $file1 = "file1.txt"
+    $file2 = "file2.txt"
+    $file3 = "file3.txt"
+    $content1 = "This is content"
+    $content2 = "This is content for alternate stream tests"
     Setup -File "$file1"
+    Setup -File "$file2" -Content $content1
+    Setup -File "$file3" -Content $content2
+    $streamContent = "content for alternate stream"
+    $streamName = "altStream1"
+  }
 
   Context "Clear-Content should actually clear content" {
     It "should clear-Content of testdrive:\$file1" {
       set-content -path testdrive:\$file1 -value "ExpectedContent" -passthru | Should be "ExpectedContent"
       clear-content -Path testdrive:\$file1
     }
+
     It "shouldn't get any content from testdrive:\$file1" {
       $result = get-content -path testdrive:\$file1
       $result | Should BeExactly $null
     }
+
+    # we could suppress the WhatIf output here if we use the testhost, but it's not necessary
+    It "The filesystem provider supports should process" -skip:(!$IsWindows) {
+      clear-content TESTDRIVE:\$file2 -WhatIf
+      "TESTDRIVE:\$file2" | should contain "This is content"
+    }
+
+    It "The filesystem provider should support ShouldProcess (reference ProviderSupportsShouldProcess member)" {
+      $cci = ((get-command clear-content).ImplementingType)::new()
+      $cci.SupportsShouldProcess | should be $true
+    }
+
+    It "Alternate streams should be cleared with clear-content" -skip:(!$IsWindows) {
+      # make sure that the content is correct
+      # this is here rather than BeforeAll because only windows can write to an alternate stream
+      set-content -path "TESTDRIVE:/$file3" -stream $streamName -value $streamContent
+      get-content -path "TESTDRIVE:/$file3" | Should be $content2
+      get-content -Path "TESTDRIVE:/$file3" -stream $streamName | should be $streamContent
+      clear-content -PATH "TESTDRIVE:/$file3" -stream $streamName
+      get-content -Path "TESTDRIVE:/$file3" | should be $content2
+      get-content -Path "TESTDRIVE:/$file3" -stream $streamName | should BeNullOrEmpty
+    }
+
+    It "the '-Stream' dynamic parameter is visible to get-command in the filesystem" {
+      try {
+        push-location TESTDRIVE:
+        (get-command clear-content -stream foo).parameters.keys -eq "stream" | should be "stream"
+      }
+      finally {
+        pop-location
+      }
+    }
+
+    It "the '-stream' dynamic parameter should not be visible to get-command in the function provider" {
+      try {
+        push-location function:
+        get-command clear-content -stream $streamName
+        throw "ExpectedExceptionNotDelivered"
+      }
+      catch {
+        $_.FullyQualifiedErrorId | should be "NamedParameterNotFound,Microsoft.PowerShell.Commands.GetCommandCommand"
+      }
+      finally {
+        pop-location
+      }
+    }
+  }
+
+  Context "Proper errors should be delivered when bad locations are specified" {
     It "should throw `"Cannot bind argument to parameter 'Path'`" when -Path is `$null" {
-      {clear-content -path $null -ea stop} | Should Throw "Cannot bind argument to parameter 'Path'"
+      try {
+        clear-content -path $null -ea stop
+        throw "expected exception was not delivered"
+      }
+      catch {
+        $_.FullyQualifiedErrorId | should be "ParameterArgumentValidationErrorNullNotAllowed,Microsoft.PowerShell.Commands.ClearContentCommand"
+      }
     }
     #[BugId(BugDatabase.WindowsOutOfBandReleases, 903880)]
     It "should throw `"Cannot bind argument to parameter 'Path'`" when -Path is `$()" {
-      {clear-content -path $() -ea stop} | Should Throw "Cannot bind argument to parameter 'Path'"
+      try {
+        clear-content -path $() -ea stop
+        throw "expected exception was not delivered"
+      }
+      catch {
+        $_.FullyQualifiedErrorId | should be "ParameterArgumentValidationErrorNullNotAllowed,Microsoft.PowerShell.Commands.ClearContentCommand"
+      }
     }
     #[DRT][BugId(BugDatabase.WindowsOutOfBandReleases, 906022)]
-    It "should throw 'PSNotSupportedException' when you set-content to an unsupported provider" -Skip:($IsLinux -Or $IsOSX) {
-      {clear-content -path HKLM:\\software\\microsoft -ea stop} | Should Throw "IContentCmdletProvider interface is not implemented"
+    It "should throw 'PSNotSupportedException' when you clear-content to an unsupported provider" {
+      $functionName = Get-NonExistantFunctionName
+      $null = new-item function:$functionName -Value { 1 }
+      try {
+        clear-content -path function:$functionName -ea Stop
+        throw "Expected exception was not thrown"
+      }
+      catch {
+        $_.FullyQualifiedErrorId | should be "NotSupported,Microsoft.PowerShell.Commands.ClearContentCommand"
+      }
+    }
+    It "should throw FileNotFound error when referencing a non-existant file" {
+      try {
+        $badFile = "TESTDRIVE:/badfilename.txt"
+        clear-content -path $badFile -ea Stop
+        throw "ExpectedExceptionNotDelivered"
+      }
+      catch {
+        $_.FullyQualifiedErrorId | should be "PathNotFound,Microsoft.PowerShell.Commands.ClearContentCommand"
+      }
+    }
+    It "should throw DriveNotFound error when referencing a non-existant drive" {
+       try {
+         $badDrive = "{0}:/file.txt" -f (Get-NonExistantDriveName)
+         clear-content -path $badDrive -ea Stop
+         thow "ExpectedExceptionNotDelivered"
+       }
+       catch {
+         $_.FullyQualifiedErrorId | Should be "DriveNotFound,Microsoft.PowerShell.Commands.ClearContentCommand"
+       }
+    }
+    # we'll use a provider qualified path to produce this error
+    It "should throw ProviderNotFound error when referencing a non-existant provider" {
+       try {
+         $badProviderPath = "{0}::C:/file.txt" -f (Get-NonExistantProviderName)
+         clear-content -path $badProviderPath -ea Stop
+         thow "ExpectedExceptionNotDelivered"
+       }
+       catch {
+         $_.FullyQualifiedErrorId | Should be "ProviderNotFound,Microsoft.PowerShell.Commands.ClearContentCommand"
+       }
     }
   }
 }