Merge pull request #222 from dusrdev/issue-220

Implements better error messages for enums (Issue #220)

Author: neuecc

src/ConsoleAppFramework/Command.cs

@@ -254,7 +254,8 @@ string Core(ITypeSymbol type, bool nullable)
                     // Enum
                     if (type.TypeKind == TypeKind.Enum)
                     {
-                        return $"if ({incrementIndex}!Enum.TryParse<{type.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)}>(commandArgs[i], true, {outArgVar})) {{ ThrowArgumentParseFailed(\"{argumentName}\", commandArgs[i]); }}{elseExpr}";
+                        string typeName = type.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat);
+                        return $"if ({incrementIndex}!Enum.TryParse<{typeName}>(commandArgs[i], true, {outArgVar})) {{ ThrowArgumentParseFailed<{typeName}>(\"{argumentName}\", commandArgs[i]); }}{elseExpr}";
                     }
 
                     // ParamsArray

src/ConsoleAppFramework/ConsoleAppBaseCode.cs

@@ -257,6 +257,11 @@ static void ThrowArgumentParseFailed(string argumentName, string value)
         throw new ArgumentParseFailedException($"Argument '{argumentName}' failed to parse, provided value: {value}");
     }
 
+    static void ThrowArgumentParseFailed<TEnum>(string argumentName, string value) where TEnum : struct, Enum {
+        var values = string.Join(", ", Enum.GetValues<TEnum>());
+        throw new ArgumentParseFailedException($"Argument '{argumentName}' is invalid. Provided value: {value}. Valid values: {values}");
+    }
+
     static void ThrowRequiredArgumentNotParsed(string name)
     {
         throw new ArgumentParseFailedException($"Required argument '{name}' was not specified.");

tests/ConsoleAppFramework.GeneratorTests/RunTest.cs

@@ -90,6 +90,23 @@ await Assert.That(verifier.Error("""
 
     }
 
+    [Test]
+    public async Task EnumErrorShowsValidValues()
+    {
+        var result = verifier.Error("""
+ConsoleApp.Log = x => Console.Write(x);           
+ConsoleApp.Run(args, (Fruit fruit) => { Console.Write(fruit); });
+
+enum Fruit
+{
+    Orange, Grape, Apple
+}
+""", "--fruit Potato");
+
+        await Assert.That(result.Stdout).Contains("Argument 'fruit' is invalid. Provided value: Potato. Valid values: Orange, Grape, Apple");
+        await Assert.That(result.ExitCode).IsEqualTo(1);
+    }
+
     [Test]
     public async Task MissingArgument()
     {