🩹 [Patch]: Partial parse of version as string (#27)

## Description

- Fixes #26

## Type of change

<!-- Use the check-boxes [x] on the options that are relevant. -->

- [ ] 📖 [Docs]
- [ ] 🪲 [Fix]
- [x] 🩹 [Patch]
- [ ] ⚠️ [Security fix]
- [ ] 🚀 [Feature]
- [ ] 🌟 [Breaking change]

## Checklist

<!-- Use the check-boxes [x] on the options that are relevant. -->

- [x] I have performed a self-review of my own code
- [x] I have commented my code, particularly in hard-to-understand areas

Author: MariusStorhaug

src/classes/public/PSSemVer.ps1

@@ -2,7 +2,7 @@
     #region Static properties
     hidden static [string] $PSSemVerPattern = '^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)' +
     '(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$'
-    hidden static [string] $LoosePSSemVerPattern = '^(?:([a-zA-Z]*)-?)?(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)' +
+    hidden static [string] $LoosePSSemVerPattern = '^(?:([a-zA-Z]*)-?)?(0|[1-9]\d*)(?:\.(0|[1-9]\d*))?(?:\.(0|[1-9]\d*))?' +
     '(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$'
     #endregion Static properties
 
@@ -109,6 +109,18 @@
         $this.Minor = if ($version.Minor -lt 0) { 0 } else { $version.Minor }
         $this.Patch = if ($version.Build -lt 0) { 0 } else { $version.Build }
     }
+
+    PSSemVer([string]$version, [string]$PreReleaseLabel, [string]$BuildLabel) {
+        if ($version -match [PSSemVer]::PSSemVerPattern) {
+            $this.Major = [int]$Matches[1]
+            $this.Minor = [int]$Matches[2]
+            $this.Patch = [int]$Matches[3]
+            $this.Prerelease = $PreReleaseLabel
+            $this.BuildMetadata = $BuildLabel
+        } else {
+            throw [ArgumentException]::new('The version string is not a valid SemVer string')
+        }
+    }
     #endregion Constructors
 
     #region Methods

src/functions/public/New-PSSemVer.ps1

@@ -48,11 +48,13 @@
 
         # The prerelease version.
         [Parameter(ParameterSetName = 'Values')]
+        [Parameter(ParameterSetName = 'String')]
         [Alias('PreReleaseLabel')]
         [string] $Prerelease = '',
 
         # The build metadata.
         [Parameter(ParameterSetName = 'Values')]
+        [Parameter(ParameterSetName = 'String')]
         [Alias('Build', 'BuildLabel')]
         [string] $BuildMetadata = '',
 
@@ -73,7 +75,7 @@
             if ([string]::IsNullOrEmpty($Version)) {
                 $Version = '0.0.0'
             }
-            return [PSSemVer]::New($Version)
+            return [PSSemVer]::New($Version, $Prerelease, $BuildMetadata)
         }
     }
 }

tests/PSSemVer.Tests.ps1

@@ -43,6 +43,14 @@
             $PSSemVer.Prerelease | Should -BeNullOrEmpty
             $PSSemVer.BuildMetadata | Should -BeNullOrEmpty
         }
+        It "New-PSSemVer -Version '1.0.0' -PreRelease 'alpha' -Build '2020-01-01'" {
+            $PSSemVer = New-PSSemVer -Version '1.0.0' -Prerelease 'alpha' -Build '2020-01-01'
+            $PSSemVer.Major | Should -Be 1
+            $PSSemVer.Minor | Should -Be 0
+            $PSSemVer.Patch | Should -Be 0
+            $PSSemVer.Prerelease | Should -Be 'alpha'
+            $PSSemVer.BuildMetadata | Should -Be '2020-01-01'
+        }
     }
 
     Describe 'Function: ConvertTo-PSSemVer' {
@@ -138,6 +146,18 @@
         It "Throws on [PSSemVer]'1.0.0-beta!1'" {
             { [PSSemVer]'1.0.0-beta!1' } | Should -Throw
         }
+        It "[PSSemVer]'1.2' => '1.2.0'" {
+            $PSSemVer = [PSSemVer]'1.2'
+            $PSSemVer.Major | Should -Be 1
+            $PSSemVer.Minor | Should -Be 2
+            $PSSemVer.Patch | Should -Be 0
+        }
+        It "[PSSemVer]'2' => '2.0.0'" {
+            $PSSemVer = [PSSemVer]'2'
+            $PSSemVer.Major | Should -Be 2
+            $PSSemVer.Minor | Should -Be 0
+            $PSSemVer.Patch | Should -Be 0
+        }
     }
 
     Describe 'Class: ToString()' {