Updated the zsh completions to escape the command name for a custom completion. (#364)

Author: CraigSiemens

Sources/ArgumentParser/Completions/ZshCompletionsGenerator.swift

@@ -185,7 +185,7 @@ extension ArgumentDefinition {
 
     case .custom:
       // Generate a call back into the command to retrieve a completions list
-      let commandName = commands.first!._commandName
+      let commandName = commands.first!._commandName.zshEscapingCommandName()
       return "{_custom_completion $_\(commandName)_commandname \(customCompletionCall(commands)) $words}"
     }
   }

Tests/ArgumentParserUnitTests/CompletionScriptTests.swift

@@ -127,6 +127,9 @@ extension CompletionScriptTests {
   struct EscapedCommand: ParsableCommand {
     @Option(help: #"Escaped chars: '[]\."#)
     var one: String
+    
+    @Argument(completion: .custom { _ in ["d", "e", "f"] })
+    var two: String
   }
 
   func testEscaped_Zsh() throws {
@@ -222,6 +225,7 @@ _escaped-command() {
     local -a args
     args+=(
         '--one[Escaped chars: '"'"'\\[\\]\\\\.]:one:'
+        ':two:{_custom_completion $_escaped_command_commandname ---completion  -- two $words}'
         '(-h --help)'{-h,--help}'[Show help information.]'
     )
     _arguments -w -s -S $args[@] && ret=0