Move validation logic from OptionsLoaded handlers to centralized option validators

Co-authored-by: waldekmastykarz <[email protected]>

Author: Copilot

DevProxy.Plugins/Behavior/GenericRandomErrorPlugin.cs

@@ -75,26 +75,32 @@ public override Option[] GetOptions()
             HelpName = "failure rate"
         };
 
+        // Add validation for rate option
+        _rateOption.Validators.Add(result =>
+        {
+            var rate = result.GetValueOrDefault<int?>();
+            if (rate is not null && (rate < 0 || rate > 100))
+            {
+                result.AddError($"Rate must be between 0 and 100. Received: {rate}");
+            }
+        });
+
         return [_rateOption];
     }
 
-    public override void OptionsLoaded(OptionsLoadedArgs e)
-    {
-        ArgumentNullException.ThrowIfNull(e);
-
-        base.OptionsLoaded(e);
-
+    public override void OptionsLoaded(OptionsLoadedArgs e)
+    {
+        ArgumentNullException.ThrowIfNull(e);
+
+        base.OptionsLoaded(e);
+
         var parseResult = e.ParseResult;
 
         var rate = parseResult.GetValueForOption<int?>(_rateOptionName, e.Options);
         if (rate is not null)
         {
-            if (rate < 0 || rate > 100)
-            {
-                throw new ArgumentOutOfRangeException($"Rate must be between 0 and 100. Received: {rate}");
-            }
-            Configuration.Rate = rate.Value;
-        }
+            Configuration.Rate = rate.Value;
+        }
     }
 
     public override Task BeforeRequestAsync(ProxyRequestArgs e)

DevProxy.Plugins/Behavior/GraphRandomErrorPlugin.cs

@@ -117,6 +117,16 @@ public override Option[] GetOptions()
             Description = "The percentage of chance that a request will fail",
             HelpName = "failure rate"
         };
+
+        // Add validation for rate option
+        _rateOption.Validators.Add(result =>
+        {
+            var rate = result.GetValueOrDefault<int?>();
+            if (rate is not null && (rate < 0 || rate > 100))
+            {
+                result.AddError($"Rate must be between 0 and 100. Received: {rate}");
+            }
+        });
 
         return [_allowedErrors, _rateOption];
     }
@@ -147,12 +157,8 @@ public override void OptionsLoaded(OptionsLoadedArgs e)
         var rate = parseResult.GetValueForOption<int?>(_rateOptionName, e.Options);
         if (rate is not null)
         {
-            if (rate < 0 || rate > 100)
-            {
-                throw new ArgumentOutOfRangeException($"Rate must be between 0 and 100. Received: {rate}");
-            }
             Configuration.Rate = rate.Value;
-        }
+        }
     }
 
     public override Task BeforeRequestAsync(ProxyRequestArgs e)

DevProxy/Commands/DevProxyCommand.cs

@@ -324,7 +324,24 @@ private void ConfigureCommand()
             HelpName = "env",
             AllowMultipleArgumentsPerToken = true,
             Arity = ArgumentArity.ZeroOrMore
-        };
+        };
+
+        // Add validation for env option format
+        _envOption.Validators.Add(result =>
+        {
+            var env = result.GetValueOrDefault<string[]?>();
+            if (env is not null)
+            {
+                foreach (var e in env)
+                {
+                    var parts = e.Split('=', 2);
+                    if (parts.Length != 2)
+                    {
+                        result.AddError($"Invalid env format: {e}. Expected format is 'key=value'.");
+                    }
+                }
+            }
+        });
 
         var options = new List<Option>
         {
@@ -489,13 +506,11 @@ private void ParseOptions(ParseResult parseResult)
         var env = parseResult.GetValueForOption<string[]?>(EnvOptionName, Options);
         if (env is not null)
         {
+            // Validation is now handled by the option validator
             _proxyConfiguration.Env = env.Select(static e =>
             {
-                // Split on first '=' only
                 var parts = e.Split('=', 2);
-                return parts.Length != 2
-                    ? throw new ArgumentException($"Invalid env format: {e}. Expected format is 'key=value'.")
-                    : new KeyValuePair<string, string>(parts[0], parts[1]);
+                return new KeyValuePair<string, string>(parts[0], parts[1]);
             }).ToDictionary(kvp => kvp.Key, kvp => kvp.Value);
         }
     }