Migrate from Errors to Exceptions for invalid use of library

.editorconfig

@@ -1,66 +1,69 @@
-root = true
-
-[*]
-indent_style = space
-indent_size = 4
-end_of_line = crlf
-charset = utf-8
-trim_trailing_whitespace = true
-insert_final_newline = true
-
-# SA1615: Element return value should be documented.
-dotnet_diagnostic.SA1615.severity = none
-
-# SA1611: Element parameters must be documented.
-dotnet_diagnostic.SA1611.severity = none
-
-# SA1633: File must have header.
-dotnet_diagnostic.SA1633.severity = none
-
-# SA1633: Generic type parameters must be documented.
-dotnet_diagnostic.SA1618.severity = none
-
-# SA1133: Each attribute should be placed in its own set of square brackets.
-dotnet_diagnostic.SA1133.severity = none
-
-# SA1600: Elements must be documented.
-dotnet_diagnostic.SA1600.severity = none
-
-# SA1601: Partial elementes should be documented.
-dotnet_diagnostic.SA1601.severity = none
-
-# SA1313: Parameter names must begin with lower case letter.
-dotnet_diagnostic.SA1313.severity = none
-
-# SA1009: Closing parenthesis should be followed by a space.
-dotnet_diagnostic.SA1009.severity = none
-
-# SA1000: The keyword 'new' should be followed by a space.
-dotnet_diagnostic.SA1000.severity = none
-
-# SA1101: Prefix local calls with this.
-dotnet_diagnostic.SA1101.severity = none
-
-# SA1309: Field should not begin with an underscore.
-dotnet_diagnostic.SA1309.severity = none
-
-# SA1602: Enumeration items should be documented.
-dotnet_diagnostic.SA1602.severity = none
-
-# CS1591: Missing XML comment for publicly visible type or member.
-dotnet_diagnostic.CS1591.severity = none
-
-# SA1200: Using directive should appear within a namespace declaration.
-dotnet_diagnostic.SA1200.severity = none
-
-# IDE0008: Use explicit type
-csharp_style_var_when_type_is_apparent = true
-
-# IDE0130: Namespace does not match folder structure
-dotnet_style_namespace_match_folder = false
-
-# IDE0023: Use block body for operators
-csharp_style_expression_bodied_operators = when_on_single_line
-
-# IDE0130: Namespace does not match folder structure
-dotnet_diagnostic.IDE0130.severity = none
+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+end_of_line = crlf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+# SA1615: Element return value should be documented.
+dotnet_diagnostic.SA1615.severity = none
+
+# SA1611: Element parameters must be documented.
+dotnet_diagnostic.SA1611.severity = none
+
+# SA1633: File must have header.
+dotnet_diagnostic.SA1633.severity = none
+
+# SA1633: Generic type parameters must be documented.
+dotnet_diagnostic.SA1618.severity = none
+
+# SA1133: Each attribute should be placed in its own set of square brackets.
+dotnet_diagnostic.SA1133.severity = none
+
+# SA1600: Elements must be documented.
+dotnet_diagnostic.SA1600.severity = none
+
+# SA1601: Partial elementes should be documented.
+dotnet_diagnostic.SA1601.severity = none
+
+# SA1313: Parameter names must begin with lower case letter.
+dotnet_diagnostic.SA1313.severity = none
+
+# SA1009: Closing parenthesis should be followed by a space.
+dotnet_diagnostic.SA1009.severity = none
+
+# SA1000: The keyword 'new' should be followed by a space.
+dotnet_diagnostic.SA1000.severity = none
+
+# SA1101: Prefix local calls with this.
+dotnet_diagnostic.SA1101.severity = none
+
+# SA1309: Field should not begin with an underscore.
+dotnet_diagnostic.SA1309.severity = none
+
+# SA1602: Enumeration items should be documented.
+dotnet_diagnostic.SA1602.severity = none
+
+# CS1591: Missing XML comment for publicly visible type or member.
+dotnet_diagnostic.CS1591.severity = none
+
+# SA1200: Using directive should appear within a namespace declaration.
+dotnet_diagnostic.SA1200.severity = none
+
+# IDE0008: Use explicit type
+csharp_style_var_when_type_is_apparent = true
+
+# IDE0130: Namespace does not match folder structure
+dotnet_style_namespace_match_folder = false
+
+# IDE0023: Use block body for operators
+csharp_style_expression_bodied_operators = when_on_single_line
+
+# IDE0130: Namespace does not match folder structure
+dotnet_diagnostic.IDE0130.severity = none
+
+# SA1642: Constructor summary documentation should begin with standard text
+dotnet_diagnostic.SA1642.severity = none

src/ErrorOr.ImplicitConverters.cs → src/ErrorOr/ErrorOr.ImplicitConverters.cs

@@ -26,6 +26,11 @@ public static implicit operator ErrorOr<TValue>(Error error)
     /// </summary>
     public static implicit operator ErrorOr<TValue>(List<Error> errors)
     {
+        if (errors.Count == 0)
+        {
+            throw new InvalidOperationException("Cannot create an ErrorOr<TValue> from an empty list of errors. Provide at least one error.");
+        }
+
         return new ErrorOr<TValue>(errors);
     }
 
@@ -34,6 +39,11 @@ public static implicit operator ErrorOr<TValue>(List<Error> errors)
     /// </summary>
     public static implicit operator ErrorOr<TValue>(Error[] errors)
     {
+        if (errors.Length == 0)
+        {
+            throw new InvalidOperationException("Cannot create an ErrorOr<TValue> from an empty list of errors. Provide at least one error.");
+        }
+
         return new ErrorOr<TValue>(errors.ToList());
     }
 }

src/ErrorOr.cs → src/ErrorOr/ErrorOr.cs

@@ -7,6 +7,14 @@ namespace ErrorOr;
 /// </summary>
 public readonly partial record struct ErrorOr<TValue> : IErrorOr<TValue>
 {
+    /// <summary>
+    /// Prevents a default <see cref="ErrorOr"/> struct from being created.
+    /// </summary>
+    public ErrorOr()
+    {
+        throw new InvalidOperationException("Default construction of ErrorOr<TValue> is invalid. Please use provided factory methods to instantiate.");
+    }
+
     private readonly TValue? _value = default;
     private readonly List<Error>? _errors = null;
 

tests/ErrorOrTests.cs → tests/ErrorOr/ErrorOr.InstantiationTests.cs

@@ -3,7 +3,7 @@ namespace Tests;
 using ErrorOr;
 using FluentAssertions;
 
-public class ErrorOrTests
+public class ErrorOrInstantiationTests
 {
     private record Person(string Name);
 
@@ -344,4 +344,36 @@ public void ImplicitCastErrorArray_WhenAccessingFirstError_ShouldReturnFirstErro
         errorOrPerson.IsError.Should().BeTrue();
         errorOrPerson.FirstError.Should().Be(errors[0]);
     }
+
+    [Fact]
+    public void CreateErrorOr_WhenUsingEmptyConstructor_ShouldThrow()
+    {
+        // Act
+#pragma warning disable SA1129 // Do not use default value type constructor
+        Func<ErrorOr<int>> errorOrInt = () => new ErrorOr<int>();
+#pragma warning restore SA1129 // Do not use default value type constructor
+
+        // Assert
+        errorOrInt.Should().ThrowExactly<InvalidOperationException>();
+    }
+
+    [Fact]
+    public void CreateErrorOr_WhenEmptyErrorsList_ShouldThrow()
+    {
+        // Act
+        Func<ErrorOr<int>> errorOrInt = () => new List<Error>();
+
+        // Assert
+        errorOrInt.Should().ThrowExactly<InvalidOperationException>();
+    }
+
+    [Fact]
+    public void CreateErrorOr_WhenEmptyErrorsArray_ShouldThrow()
+    {
+        // Act
+        Func<ErrorOr<int>> errorOrInt = () => Array.Empty<Error>();
+
+        // Assert
+        errorOrInt.Should().ThrowExactly<InvalidOperationException>();
+    }
 }