Add test coverage for Command discovery and requires (#2285)

test/powershell/Language/Scripting/Requires.Tests.ps1

@@ -0,0 +1,28 @@
+Describe "Requires tests" -Tags "CI" {
+    Context "Parser error" {
+        
+        $testcases = @(
+                        @{command = "#requiresappID`r`n$foo = 1; $foo" ; testname = "appId with newline"}
+                        @{command = "#requires -version A `r`n$foo = 1; $foo" ; testname = "version as character"}
+                        @{command = "#requires -version 2b `r`n$foo = 1; $foo" ; testname = "alphanumeric version"}
+                        @{command = "#requires -version 1. `r`n$foo = 1; $foo" ; testname = "version with dot"}
+                        @{command = "#requires -version '' `r`n$foo = 1; $foo" ; testname = "empty version"}
+                        @{command = "#requires -version 1.0. `r`n$foo = 1; $foo" ; testname = "version with two dots"}
+                        @{command = "#requires -version 1.A `r`n$foo = 1; $foo" ; testname = "alphanumeric version with dots"}
+                    )
+        
+        It "throws ParserException - <testname>" -TestCases $testcases {
+            param($command)
+            try
+            {
+                [scriptblock]::Create($command)
+                throw "'$command' should have thrown ParserError"
+            }
+            catch
+            {
+                $_.FullyQualifiedErrorId | Should Be "ParseException"
+            }
+        }
+    }
+
+}

test/powershell/enginecore/CommandDiscovery.Tests.ps1

@@ -0,0 +1,105 @@
+Describe "Command Discovery tests" -Tags "CI" {
+
+    BeforeAll {
+        setup -f testscript.ps1 -content "'This script should not run. Running from testscript.ps1'"
+        setup -f testscripp.ps1 -content "'This script should not run. Running from testscripp.ps1'"
+
+        $TestCasesCommandNotFound = @(
+                        @{command = 'CommandThatDoesnotExist' ; testName = 'Non-existent command'}
+                        @{command = 'testscrip?.ps1' ; testName = 'Multiple matches for filename'}
+                        @{command = "demo" + [System.IO.Path]::DirectorySeparatorChar; testName = 'Non existent command with directory separator'}
+                        @{command = [System.IO.Path]::DirectorySeparatorChar; testName = 'Directory separator'}
+                        @{command = 'environment::\path'; testName = 'Provider qualified path'}                        
+                       )
+    }
+        
+    It "<testName>" -TestCases $TestCasesCommandNotFound {
+        param($command)
+        try
+        {
+            & $command
+            throw "Should not have found command: '$command'"
+        }
+        catch
+        {
+            $_.FullyQualifiedErrorId | Should Be 'CommandNotFoundException'
+        }
+    }
+
+    It "Command lookup with duplicate paths" {                            
+        $previousPath = $env:PSMODULEPATH
+
+        try
+        {
+            New-Item -Path "$TestDrive\TestFunctionA" -ItemType Directory
+            New-Item -Path "$TestDrive\\TestFunctionA\TestFunctionA.psm1" -Value "function TestFunctionA {}" | Out-Null
+
+            $env:PSMODULEPATH = "$TestDrive" + [System.IO.Path]::PathSeparator + "$TestDrive"
+            (Get-command 'TestFunctionA').count | Should Be 1               
+        }
+        finally
+        {
+            $env:PSMODULEPATH = $previousPath        
+        }
+    }
+
+    It "Alias can be set for a cmdlet" {
+
+            Set-Alias 'AliasCommandDiscoveryTest' Get-ChildItem
+            $commands = (Get-Command 'AliasCommandDiscoveryTest')
+
+            $commands.Count | Should Be 1        
+            $aliasResult = $commands -as [System.Management.Automation.AliasInfo] 
+            $aliasResult | Should BeOfType [System.Management.Automation.AliasInfo]
+            $aliasResult.Name | Should Be 'AliasCommandDiscoveryTest'
+    }
+
+    It "Cyclic aliases - direct" {
+        try
+        {
+            Set-Alias CyclicAliasA CyclicAliasB -Force
+            Set-Alias CyclicAliasB CyclicAliasA -Force
+            & CyclicAliasA
+            throw "Execution should not reach here. '& CyclicAliasA' should have thrown."
+        }
+        catch
+        {
+            $_.FullyQualifiedErrorId | Should Be 'CommandNotFoundException'
+        }
+    }
+
+    It "Cyclic aliases - indirect" {
+        try
+        {
+            Set-Alias CyclicAliasA CyclicAliasB -Force
+            Set-Alias CyclicAliasB CyclicAliasC -Force
+            Set-Alias CyclicAliasC CyclicAliasA -Force
+            & CyclicAliasA
+            throw "Execution should not reach here. '& CyclicAliasA' should have thrown."
+        }
+        catch
+        {
+            $_.FullyQualifiedErrorId | Should Be 'CommandNotFoundException'
+        }
+    }
+
+    It "Get-Command should return only CmdletInfo, FunctionInfo, AliasInfo or FilterInfo" {
+         
+         $commands = Get-Command
+         $commands.Count | Should BeGreaterThan 0
+
+        foreach($command in $commands)
+        {
+            $command.GetType().Name | should be @("AliasInfo","FunctionInfo","CmdletInfo","FilterInfo")
+        }
+    }
+
+    It "Non-existent commands with wildcard should not write errors" {
+        Get-Command "CommandDoesNotExist*" -ErrorVariable ev -ErrorAction SilentlyContinue
+        $ev | Should BeNullOrEmpty
+    }
+
+    It "Get- is prepended to commands" {
+        (& 'location').Path | Should Be (get-location).Path
+    }
+}