Add AsOneString parameter to ConvertTo-Base64 for single string encoding

src/functions/public/ConvertTo-Base64.ps1

@@ -6,6 +6,8 @@
         .DESCRIPTION
         This function takes a string or array of strings as input and converts them to base64 encoded strings using UTF-8 encoding.
         It accepts input from the pipeline and can process string values directly or as an array.
+
+        By default, each string is encoded individually. Use the -AsOneString parameter to join all inputs with newlines and encode as a single string.
 
         .EXAMPLE
         "Hello World" | ConvertTo-Base64
@@ -28,6 +30,26 @@
 
         Converts each string in the array to its base64 encoded equivalent.
 
+        .EXAMPLE
+        @("Hello", "World") | ConvertTo-Base64 -AsOneString
+
+        Output:
+        ```powershell
+        SGVsbG8KV29ybGQ=
+        ```
+
+        Joins all strings with newlines and encodes them as a single base64 string.
+
+        .EXAMPLE
+        Get-Content -Path "file.txt" | ConvertTo-Base64 -AsOneString
+
+        Output:
+        ```powershell
+        VGhpcyBpcyB0aGUgY29udGVudCBvZiB0aGUgZmlsZQp3aXRoIG11bHRpcGxlIGxpbmVzLg==
+        ```
+
+        Reads the file content and encodes all lines as a single base64 string, similar to the Linux base64 utility.
+
         .OUTPUTS
         System.String
 
@@ -52,12 +74,35 @@
         # The encoding to use when converting the string to bytes.
         [Parameter()]
         [ValidateSet('UTF8', 'UTF7', 'UTF32', 'ASCII', 'Unicode', 'BigEndianUnicode', 'Latin1')]
-        [string] $Encoding = 'UTF8'
+        [string] $Encoding = 'UTF8',
+
+        # Join all input strings with newlines and encode as a single string.
+        [Parameter()]
+        [switch] $AsOneString
     )
 
+    begin {
+        if ($AsOneString) {
+            [System.Collections.Generic.List[string]]$allStrings = @()
+        }
+    }
+
     process {
-        foreach ($item in $String) {
-            [Convert]::ToBase64String([System.Text.Encoding]::$Encoding.GetBytes($item))
+        if ($AsOneString) {
+            foreach ($item in $String) {
+                $allStrings.Add($item)
+            }
+        } else {
+            foreach ($item in $String) {
+                [Convert]::ToBase64String([System.Text.Encoding]::$Encoding.GetBytes($item))
+            }
+        }
+    }
+
+    end {
+        if ($AsOneString -and $allStrings.Count -gt 0) {
+            $joinedString = $allStrings -join [Environment]::NewLine
+            [Convert]::ToBase64String([System.Text.Encoding]::$Encoding.GetBytes($joinedString))
         }
     }
 }

test.txt

@@ -0,0 +1,3 @@
+hello some world!
+
+here is my decoded content

tests/Base64.Tests.ps1

@@ -70,6 +70,17 @@ Describe 'Base64' {
             $result[1] | Should -Be 'TGluZSAy'
             $result[2] | Should -Be 'TGluZSAz'
         }
+
+        It "File content piped to ConvertTo-Base64 with AsOneString" {
+            $testFilePath = '/tmp/base64_test/test_content.txt'
+            $result = Get-Content -Path $testFilePath | ConvertTo-Base64 -AsOneString
+            $result | Should -Be 'TGluZSAxCkxpbmUgMgpMaW5lIDM='
+        }
+
+        It "@('Hello', 'World') | ConvertTo-Base64 -AsOneString -> single string" {
+            $result = @('Hello', 'World') | ConvertTo-Base64 -AsOneString
+            $result | Should -Be 'SGVsbG8KV29ybGQ='
+        }
     }
     Context 'Function: ConvertFrom-Base64' {
         It "ConvertFrom-Base64 -Base64String 'VGhpc0lzQU5pY2VTdHJpbmc=' -> ThisIsANiceString" {