From 2af370ef21d25d57b68bf8ebf826f5dd1cdeabee Mon Sep 17 00:00:00 2001
From: Christian Jones <chjones@aleph0.com>
Date: Sat, 9 Apr 2022 17:57:04 -0400
Subject: [PATCH 1/2] Error instead of exception for FileSystemInfo null paths

---
 .../Binding/TypeConversionTests.cs              | 17 ++++++++++++++++-
 .../ArgumentConverter.StringConverters.cs       | 15 +++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/System.CommandLine.Tests/Binding/TypeConversionTests.cs b/src/System.CommandLine.Tests/Binding/TypeConversionTests.cs
index 93edfe7959..85dfdf50be 100644
--- a/src/System.CommandLine.Tests/Binding/TypeConversionTests.cs
+++ b/src/System.CommandLine.Tests/Binding/TypeConversionTests.cs
@@ -5,8 +5,8 @@
 using System.Collections.Generic;
 using System.CommandLine.Utility;
 using System.IO;
-using FluentAssertions;
 using System.Linq;
+using FluentAssertions;
 using Xunit;
 
 namespace System.CommandLine.Tests.Binding
@@ -65,6 +65,21 @@ public void Command_argument_of_FileInfo_returns_null_when_argument_is_not_provi
                   .BeNull();
         }
 
+        [Fact]
+        public void Argument_of_FileInfo_that_is_empty_results_in_an_informative_error()
+        {
+            var option = new Option<FileInfo>("--file");
+            var result = option.Parse(new string[] { "--file", "" });
+
+            result.Errors
+                  .Should()
+                  .ContainSingle()
+                  .Which
+                  .Message
+                  .Should()
+                  .Contain("Cannot parse argument '' for option '--file'");
+        }
+
         [Fact]
         public void Argument_of_array_of_FileInfo_can_be_called_without_custom_conversion_logic()
         {
diff --git a/src/System.CommandLine/Binding/ArgumentConverter.StringConverters.cs b/src/System.CommandLine/Binding/ArgumentConverter.StringConverters.cs
index 3314be2c01..24b2b8fb7b 100644
--- a/src/System.CommandLine/Binding/ArgumentConverter.StringConverters.cs
+++ b/src/System.CommandLine/Binding/ArgumentConverter.StringConverters.cs
@@ -62,6 +62,11 @@ internal static partial class ArgumentConverter
 
         [typeof(DirectoryInfo)] = (string path, out object? value) =>
         {
+            if (String.IsNullOrEmpty(path))
+            {
+                value = default;
+                return false;
+            }
             value = new DirectoryInfo(path);
             return true;
         },
@@ -80,12 +85,22 @@ internal static partial class ArgumentConverter
 
         [typeof(FileInfo)] = (string path, out object? value) =>
         {
+            if (String.IsNullOrEmpty(path))
+            {
+                value = default;
+                return false;
+            }
             value = new FileInfo(path);
             return true;
         },
 
         [typeof(FileSystemInfo)] = (string path, out object? value) =>
         {
+            if (String.IsNullOrEmpty(path))
+            {
+                value = default;
+                return false;
+            }
             if (Directory.Exists(path))
             {
                 value = new DirectoryInfo(path);

From b524516dc42a4dc7bfb9f7909497f2c9081e42d6 Mon Sep 17 00:00:00 2001
From: Christian Jones <chjones@aleph0.com>
Date: Sat, 9 Apr 2022 17:59:28 -0400
Subject: [PATCH 2/2] Revert autoformat

---
 src/System.CommandLine.Tests/Binding/TypeConversionTests.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/System.CommandLine.Tests/Binding/TypeConversionTests.cs b/src/System.CommandLine.Tests/Binding/TypeConversionTests.cs
index 85dfdf50be..0e15ae1af4 100644
--- a/src/System.CommandLine.Tests/Binding/TypeConversionTests.cs
+++ b/src/System.CommandLine.Tests/Binding/TypeConversionTests.cs
@@ -5,8 +5,8 @@
 using System.Collections.Generic;
 using System.CommandLine.Utility;
 using System.IO;
-using System.Linq;
 using FluentAssertions;
+using System.Linq;
 using Xunit;
 
 namespace System.CommandLine.Tests.Binding