Merge pull request #885 from dscho/support-gfw-rc-versions

Avoid warning when using -rc versions of Git for Windows

src/CheckRequirements.ps1

@@ -8,8 +8,12 @@ if (!(Get-Command git -TotalCount 1 -ErrorAction SilentlyContinue)) {
     return
 }
 
-if ([string](git --version 2> $null) -match '(?<ver>\d+(?:\.\d+)+)(?<g4w>\.windows|\.vfs)?') {
-    $script:GitVersion = [System.Version]$Matches['ver']
+function Test-GitVersion ($version = $([string](git --version 2> $null))) {
+    if ($version -notmatch '(?<ver>\d+(?:\.\d+)+)(?<g4w>(?<rc>[-.]rc\d+)?\.windows|\.vfs)?') {
+        Write-Warning "posh-git could not parse Git version ($version)"
+        $script:GitVersion = $version
+        return $false
+    }
 
     # On Windows, check if Git is not "Git for Windows"
     if ((($PSVersionTable.PSVersion.Major -le 5) -or $IsWindows) -and !$Matches['g4w']) {
@@ -19,8 +23,12 @@ if ([string](git --version 2> $null) -match '(?<ver>\d+(?:\.\d+)+)(?<g4w>\.windo
             Write-Warning 'You appear to have an unsupported Git distribution; setting $GitPromptSettings.AnsiConsole = $false. posh-git recommends Git for Windows.'
         }
     }
+
+    $script:GitVersion = [System.Version]$Matches['ver']
+
+    return $GitVersion -ge $requiredVersion
 }
 
-if ($GitVersion -lt $requiredVersion) {
+if (!(Test-GitVersion)) {
     Write-Warning "posh-git requires Git $requiredVersion or better. You have $GitVersion."
 }

test/CheckRequirements.Tests.ps1

@@ -0,0 +1,45 @@
+# Not using BeforeAll because discovery doesn't like InModuleScope without posh-git loaded
+. $PSScriptRoot\Shared.ps1
+
+Describe 'Test-GitVersion' {
+    InModuleScope 'posh-git' {
+        It 'Returns true for Git for Windows newer than 2.15 (<_>)' -ForEach @(
+            'git version 2.33.0.rc2.windows.1',
+            'git version 2.33.0-rc2.windows.1',
+            'git version 2.31.0.vfs.0.1',
+            'git version 2.15.0.windows.0',
+            'git version 2.100.0.windows.0',
+            'git version 3.0.0.windows.0'
+        ) {
+            Mock Write-Warning {}
+
+            Test-GitVersion $_ | Should -Be $true
+
+            Should -Not -Invoke Write-Warning
+        }
+
+        It 'Returns false for Git for Windows older than 2.15 (<_>)' -ForEach @(
+            'git version 0.1.0.windows',
+            'git version 1.99.0.windows',
+            'git version 2.14.0.windows'
+        ) {
+            Mock Write-Warning {}
+
+            Test-GitVersion $_ | Should -Be $false
+
+            Should -Not -Invoke Write-Warning
+        }
+
+        It 'Returns false for unparseable version (<_>)' -ForEach @(
+            'git version 1'
+        ) {
+            Mock Write-Warning {} -Verifiable -ParameterFilter { $Message -like '*could not parse*' }
+
+            Test-GitVersion $_ | Should -Be $false
+
+            Should -InvokeVerifiable Write-Warning
+        }
+
+        # TODO: Test Cygwin warning and POSHGIT_CYGWIN_WARNING
+    }
+}