Warn when 'Get-' prefix was omitted.

RuleDocumentation/AvoidUsingCmdletAliases.md

@@ -5,7 +5,7 @@
 ## Description
 
 An alias is an alternate name or nickname for a CMDLet or for a command element, such as a function, script, file, or executable file.
-You can use the alias instead of the command name in any Windows PowerShell commands.
+You can use the alias instead of the command name in any Windows PowerShell commands. There are also implicit aliases: When PowerShell cannot find the cmdlet name, it will try to append `Get-` to the command as a last resort before, therefore e.g. `verb` will excute `Get-Verb`.
 
 Every PowerShell author learns the actual command names, but different authors learn and use different aliases. Aliases can make code difficult to read, understand and
 impact availability.

Rules/AvoidAlias.cs

@@ -1,14 +1,5 @@
-//
-// Copyright (c) Microsoft Corporation.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-// THE SOFTWARE.
-//
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
 
 using System;
 using System.Collections.Generic;
@@ -104,38 +95,54 @@ public IEnumerable<DiagnosticRecord> AnalyzeScript(Ast ast, string fileName)
             IEnumerable<Ast> foundAsts = ast.FindAll(testAst => testAst is CommandAst, true);
 
             // Iterates all CommandAsts and check the command name.
-            foreach (Ast foundAst in foundAsts)
+            foreach (CommandAst cmdAst in foundAsts)
             {
-                CommandAst cmdAst = (CommandAst)foundAst;
-
                 // Check if the command ast should be ignored
                 if (IgnoreCommandast(cmdAst))
                 {
                     continue;
                 }
 
-                string aliasName = cmdAst.GetCommandName();
+                string commandName = cmdAst.GetCommandName();
 
                 // Handles the exception caused by commands like, {& $PLINK $args 2> $TempErrorFile}.
                 // You can also review the remark section in following document,
                 // MSDN: CommandAst.GetCommandName Method
-                if (aliasName == null
-                    || whiteList.Contains<string>(aliasName, StringComparer.OrdinalIgnoreCase))
+                if (commandName == null
+                    || whiteList.Contains<string>(commandName, StringComparer.OrdinalIgnoreCase))
                 {
                     continue;
                 }
 
-                string cmdletName = Helper.Instance.GetCmdletNameFromAlias(aliasName);
-                if (!String.IsNullOrEmpty(cmdletName))
+                string cmdletNameIfCommandNameWasAlias = Helper.Instance.GetCmdletNameFromAlias(commandName);
+                if (!String.IsNullOrEmpty(cmdletNameIfCommandNameWasAlias))
                 {
                     yield return new DiagnosticRecord(
-                        string.Format(CultureInfo.CurrentCulture, Strings.AvoidUsingCmdletAliasesError, aliasName, cmdletName),
+                        string.Format(CultureInfo.CurrentCulture, Strings.AvoidUsingCmdletAliasesError, commandName, cmdletNameIfCommandNameWasAlias),
                         GetCommandExtent(cmdAst),
                         GetName(),
                         DiagnosticSeverity.Warning,
                         fileName,
-                        aliasName,
-                        suggestedCorrections: GetCorrectionExtent(cmdAst, cmdletName));
+                        commandName,
+                        suggestedCorrections: GetCorrectionExtent(cmdAst, cmdletNameIfCommandNameWasAlias));
+                }
+
+                var isNativeCommand = Helper.Instance.GetCommandInfo(commandName) != null;
+                if (!isNativeCommand)
+                {
+                    var commdNameWithGetPrefix = $"Get-{commandName}";
+                    var cmdletNameIfCommandWasMissingGetPrefix = Helper.Instance.GetCommandInfo($"Get-{commandName}");
+                    if (cmdletNameIfCommandWasMissingGetPrefix != null)
+                    {
+                        yield return new DiagnosticRecord(
+                            string.Format(CultureInfo.CurrentCulture, Strings.AvoidUsingCmdletAliasesMissingGetPrefixError, commandName, commdNameWithGetPrefix),
+                            GetCommandExtent(cmdAst),
+                            GetName(),
+                            DiagnosticSeverity.Warning,
+                            fileName,
+                            commandName,
+                            suggestedCorrections: GetCorrectionExtent(cmdAst, commdNameWithGetPrefix));
+                    }
                 }
             }
         }

Rules/Strings.resx

@@ -118,10 +118,10 @@
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
   <data name="AvoidUsingCmdletAliasesDescription" xml:space="preserve">
-    <value>An alias is an alternate name or nickname for a cmdlet or for a command element, such as a function, script, file, or executable file. But when writing scripts that will potentially need to be maintained over time, either by the original author or another Windows PowerShell scripter, please consider using full cmdlet name instead of alias. Aliases can introduce these problems, readability, understandability and availability.</value>
+    <value>An alias is an alternate name or nickname for a cmdlet or for a command element, such as a function, script, file, or executable file. An implicit alias is also the omission of the 'Get-' prefix for commands with this prefix. But when writing scripts that will potentially need to be maintained over time, either by the original author or another Windows PowerShell scripter, please consider using full cmdlet name instead of alias. Aliases can introduce these problems, readability, understandability and availability.</value>
   </data>
   <data name="AvoidUsingCmdletAliasesCommonName" xml:space="preserve">
-    <value>Avoid Using Cmdlet Aliases</value>
+    <value>Avoid Using Cmdlet Aliases or omitting the 'Get-' prefix.</value>
   </data>
   <data name="AvoidUsingEmptyCatchBlockDescription" xml:space="preserve">
     <value>Empty catch blocks are considered poor design decisions because if an error occurs in the try block, this error is simply swallowed and not acted upon. While this does not inherently lead to bad things. It can and this should be avoided if possible. To fix a violation of this rule, using Write-Error or throw statements in catch blocks.</value>
@@ -1005,4 +1005,7 @@
   <data name="AvoidAssignmentToAutomaticVariableName" xml:space="preserve">
     <value>AvoidAssignmentToAutomaticVariable</value>
   </data>
+  <data name="AvoidUsingCmdletAliasesMissingGetPrefixError" xml:space="preserve">
+    <value>'{0}' is implicitly aliasing '{1}' because it is missing the 'Get-' prefix. This can introduce possible problems and make scripts hard to maintain. Please consider changing command to its full name.</value>
+  </data>
 </root>

Tests/Rules/AvoidUsingAlias.tests.ps1

@@ -26,6 +26,11 @@ Describe "AvoidUsingAlias" {
             Test-CorrectionExtent $violationFilepath $violations[1] 1 'cls' 'Clear-Host'
             $violations[1].SuggestedCorrections[0].Description | Should -Be 'Replace cls with Clear-Host'
         }
+
+        It "warns when 'Get-' prefix was omitted" {
+            $violations = Invoke-ScriptAnalyzer -ScriptDefinition 'verb' | Where-Object { $_.RuleName -eq $violationName }
+            $violations.Count | Should -Be 1
+        }
     }
 
     Context "Violation Extent" {
@@ -95,5 +100,10 @@ Configuration MyDscConfiguration {
             $violations = Invoke-ScriptAnalyzer -ScriptDefinition "CD" -Settings $settings -IncludeRule $violationName
             $violations.Count | Should -Be 0
         }
+
+        It "do not warn when about Get-* completed cmdlets when the command exists natively on Unix platforms" -skip:(!$IsLinux -and !$IsmacOS) {
+            $violations = Invoke-ScriptAnalyzer -ScriptDefinition 'date' | Where-Object { $_.RuleName -eq $violationName }
+            $violations.Count | Should -Be 0
+        }
     }
 }