Add tests for issue #201

src/TestStack.BDDfy.Tests/HumanizerTests.cs

@@ -89,6 +89,18 @@ public void ReportsIllegalExampleStepNames(string stepName, string expectedStepT
             exception.ShouldBeOfType<ArgumentException>();
         }
 
+        [Theory]
+        [InlineData("my__step_method", "my step method")]
+        [InlineData("Method__Name", "Method name")]
+        [InlineData("my__step__method", "My <step> method")]
+        [InlineData("Given__value__is_set", "Given <value> is set")]
+        [InlineData("a__b", "A b")]
+        [InlineData("step____name", "Step name")]
+        public void DoubleUnderscoreWithoutClosingPair_DoesNotCauseStackOverflow(string stepName, string expectedStepTitle)
+        {
+            Humanizer.Humanize(stepName).ShouldBe(expectedStepTitle);
+        }
+
         [Theory]
         [InlineData("")]
         [InlineData(" ")]

src/TestStack.BDDfy.Tests/Scanner/ReflectiveScanner/WhenStepMethodNameHasDoubleUnderscores.cs

@@ -0,0 +1,92 @@
+using System.Linq;
+using Shouldly;
+using Xunit;
+
+namespace TestStack.BDDfy.Tests.Scanner.ReflectiveScanner
+{
+    /// <summary>
+    /// Regression test for https://github.com/TestStack/TestStack.BDDfy/issues/201
+    /// A double underscore in a step method name should not cause a stack overflow.
+    /// </summary>
+    public class WhenStepMethodNameHasDoubleUnderscores
+    {
+        private class StoryWithDoubleUnderscoreMethodNames
+        {
+            public bool GivenExecuted { get; private set; }
+            public bool WhenExecuted { get; private set; }
+            public bool ThenExecuted { get; private set; }
+
+            public void Given_a__setup_step() => GivenExecuted = true;
+            public void When_something__happens() => WhenExecuted = true;
+            public void Then_the__result_is_correct() => ThenExecuted = true;
+        }
+
+        private class StoryWithPascalCaseDoubleUnderscore
+        {
+            public bool Executed { get; private set; }
+
+            public void GivenSome__Precondition() => Executed = true;
+            public void WhenAction__IsPerformed() { }
+            public void ThenOutcome__IsExpected() { }
+        }
+
+        [Fact]
+        public void DoesNotThrowForSnakeCaseWithDoubleUnderscore()
+        {
+            var story = new StoryWithDoubleUnderscoreMethodNames();
+
+            var engine = story.LazyBDDfy();
+            var exception = Record.Exception(() => engine.Run());
+
+            exception.ShouldBeNull();
+        }
+
+        [Fact]
+        public void AllStepsAreExecuted()
+        {
+            var story = new StoryWithDoubleUnderscoreMethodNames();
+            story.BDDfy();
+
+            story.GivenExecuted.ShouldBeTrue();
+            story.WhenExecuted.ShouldBeTrue();
+            story.ThenExecuted.ShouldBeTrue();
+        }
+
+        [Fact]
+        public void StepTitlesAreGeneratedCorrectly_SnakeCase()
+        {
+            var story = new StoryWithDoubleUnderscoreMethodNames();
+            var result = story.BDDfy();
+
+            var steps = result.Scenarios.First().Steps.Select(s => s.Title).ToList();
+
+            steps.ShouldContain("Given a setup step");
+            steps.ShouldContain("When something happens");
+            steps.ShouldContain("Then the result is correct");
+        }
+
+        [Fact]
+        public void DoesNotThrowForPascalCaseWithDoubleUnderscore()
+        {
+            var story = new StoryWithPascalCaseDoubleUnderscore();
+
+            var engine = story.LazyBDDfy();
+            var exception = Record.Exception(() => engine.Run());
+
+            exception.ShouldBeNull();
+        }
+
+        [Fact]
+        public void StepTitlesAreGeneratedCorrectly_PascalCase()
+        {
+            var story = new StoryWithPascalCaseDoubleUnderscore();
+            var result = story.BDDfy();
+
+            var steps = result.Scenarios.First().Steps.Select(s => s.Title).ToList();
+
+            steps.ShouldContain("Given some precondition");
+            steps.ShouldContain("When action is performed");
+            steps.ShouldContain("Then outcome is expected");
+        }
+    }
+}