refactor: Simplify readability of the code

Author: NelsonBN

src/Options/FormatsOption.cs

@@ -18,9 +18,7 @@ public FormatsOption()
         Validators.Add(static result =>
         {
             var values = result.Tokens
-                .Select(token => token.Value)
-                .Where(value => !string.IsNullOrWhiteSpace(value))
-                .ToArray();
+                .Select(token => token.Value);
             foreach(var value in values)
             {
                 if(!_allowedValues.Contains(value))

tests/PowerUtils.BenchmarkDotnet.Reporter.Tests/Options/FormatOptionTests.cs

@@ -65,7 +65,7 @@ public void When_Format_Is_Valid_Shouldnt_Have_Validation_Error(string format)
     [InlineData("invalid-format")]
     [InlineData("csv")]
     [InlineData("html")]
-    public void When_Format_Is_Invalid_Should_Have_Validation_Error(string? format)
+    public void When_Format_Is_Invalid_Should_Have_Validation_Error(string format)
     {
         // Arrange
         var command = "compare";
@@ -85,4 +85,29 @@ public void When_Format_Is_Invalid_Should_Have_Validation_Error(string? format)
         firstOptionResult?.Errors.Count().ShouldBe(1);
         firstOptionResult?.Errors.ShouldContain(e => e.Message == $"Invalid format '{format}'. Allowed values: console, markdown, json, hit-txt");
     }
+
+    [Theory]
+    [InlineData("")]
+    [InlineData(" ")]
+    [InlineData(null)]
+    public void When_Format_Isnt_Defined_Should_Have_Validation_Error(string? format)
+    {
+        // Arrange
+        var command = "compare";
+        var option = "--format";
+
+        var toolCommands = new ToolCommands(_provider);
+        var compareCommand = toolCommands.Subcommands.Single(c => c.Name == command);
+        var formatsOption = compareCommand.Options.Single(o => o.Name == option);
+        var validation = formatsOption.Validators.Single();
+
+
+        // Act
+        var parseResult = toolCommands.Parse($"{command} {option} {format}");
+        var firstOptionResult = parseResult.GetResult(formatsOption);
+
+        // Assert
+        firstOptionResult?.Errors.Count().ShouldBe(1);
+        firstOptionResult?.Errors.ShouldContain(e => e.Message == "Required argument missing for option: '--format'.");
+    }
 }