fix(argument parser): Return empty when containing empty args

Author: kylef

CHANGELOG.md

@@ -10,6 +10,8 @@
 - Only print errors in red if the output terminal supports ANSI colour codes.
   [#58](https://github.com/kylef/Commander/pull/58)
 
+- `ArgumentParser.isEmpty` will now return empty for empty arguments.
+
 ## 0.8.0
 
 ### Enhancements

Sources/Commander/ArgumentParser.swift

@@ -1,4 +1,4 @@
-private enum Arg : CustomStringConvertible {
+private enum Arg : CustomStringConvertible, Equatable {
   /// A positional argument
   case argument(String)
 
@@ -32,6 +32,11 @@ private enum Arg : CustomStringConvertible {
 }
 
 
+private func == (lhs: Arg, rhs: Arg) -> Bool {
+  return lhs.description == rhs.description
+}
+
+
 public struct ArgumentParserError : Error, Equatable, CustomStringConvertible {
   public let description: String
 
@@ -77,8 +82,8 @@ public final class ArgumentParser : ArgumentConvertible, CustomStringConvertible
     return arguments.map { $0.description }.joined(separator: " ")
   }
 
-  public var isEmpty:Bool {
-    return arguments.isEmpty
+  public var isEmpty: Bool {
+    return arguments.first { $0 != .argument("") } == nil
   }
 
   public var remainder:[String] {

Tests/CommanderTests/ArgumentParserSpec.swift

@@ -10,6 +10,22 @@ public func testArgumentParser() {
       parser = ArgumentParser(arguments: ["first", "-f", "--verbose", "middle", "end", "--varOption", "varValue1", "--varOption", "varValue2"])
     }
 
+    $0.describe("isEmpty") {
+      $0.it("returns when not empty") {
+        parser = ArgumentParser(arguments: [])
+        try expect(parser.isEmpty).to.beTrue()
+      }
+
+      $0.it("returns when not empty") {
+        try expect(parser.isEmpty).to.beFalse()
+      }
+
+      $0.it("returns empty when containing empty arguments") {
+        parser = ArgumentParser(arguments: [""])
+        try expect(parser.isEmpty).to.beTrue()
+      }
+    }
+
     $0.describe("shifting") {
       $0.it("provides first positional argument") {
         try expect(parser.shift()) == "first"