From 122198d9897cf04d11a9be0c725852906b365726 Mon Sep 17 00:00:00 2001
From: Charles Oliver Nutter <headius@headius.com>
Date: Mon, 17 Jul 2023 18:18:24 -0500
Subject: [PATCH] Add test case for JRubyMethod.checkArity behavior

See jruby/jruby#7860
---
 .../org/jruby/test/TestMethodFactories.java   | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/core/src/test/java/org/jruby/test/TestMethodFactories.java b/core/src/test/java/org/jruby/test/TestMethodFactories.java
index 4b837c93721..b10b8e8219a 100644
--- a/core/src/test/java/org/jruby/test/TestMethodFactories.java
+++ b/core/src/test/java/org/jruby/test/TestMethodFactories.java
@@ -33,6 +33,7 @@
 import org.jruby.RubyMethod;
 import org.jruby.RubyModule;
 import org.jruby.anno.JRubyMethod;
+import org.jruby.exceptions.ArgumentError;
 import org.jruby.internal.runtime.methods.DynamicMethod;
 import org.jruby.runtime.ThreadContext;
 import org.jruby.runtime.builtin.IRubyObject;
@@ -47,6 +48,8 @@ public void testInvocationMethodFactory() {
         RubyModule mod = runtime.defineModule("Wombat" + hashCode());
 
         mod.defineAnnotatedMethods(MyBoundClass.class);
+
+        confirmCheckArity(mod);
     }
 
     public void testReflectionMethodFactory() {
@@ -66,6 +69,28 @@ private void confirmMethods(RubyModule mod) {
                 mod.searchMethod("four_arg_method").call(context, mod, mod.getMetaClass(), "four_arg_method", new IRubyObject[] {nil, nil, nil, nil}).isTrue());
     }
 
+    // jruby/jruby#7851: Restore automatic arity checking with an opt-out
+    private void confirmCheckArity(RubyModule mod) {
+        ThreadContext context = runtime.getCurrentContext();
+
+        verifyCheckArityError(mod, context, "optWithCheckArityTrue", true);
+        verifyCheckArityError(mod, context, "optWithCheckArityFalse", false);
+        verifyCheckArityError(mod, context, "optWithCheckArityDefault", true);
+    }
+
+    private static void verifyCheckArityError(RubyModule mod, ThreadContext context, String method, boolean error) {
+        if (error) {
+            try {
+                mod.searchMethod(method).call(context, mod, mod.getMetaClass(), method);
+                if (error) fail("optCheckArityTrue should error with zero args");
+            } catch (ArgumentError ae) {
+                // pass
+                if (!error) fail(method + " should not error with zero args");
+                return;
+            }
+        }
+    }
+
     public static class MyBoundClass {
         // void methods should work
         @JRubyMethod
@@ -77,6 +102,24 @@ public static void void_returning_method(IRubyObject obj) {}
         public static IRubyObject four_arg_method(IRubyObject self, IRubyObject[] obj) {
             return self.getRuntime().getTrue();
         }
+
+        // jruby/jruby#7851: Restore automatic arity checking with an opt-out
+        @JRubyMethod(required = 1, optional = 1, checkArity = true)
+        public static IRubyObject optWithCheckArityTrue(ThreadContext context, IRubyObject self, IRubyObject[] args) {
+            return context.tru;
+        }
+
+        // jruby/jruby#7851: Restore automatic arity checking with an opt-out
+        @JRubyMethod(required = 1, optional = 1, checkArity = false)
+        public static IRubyObject optWithCheckArityFalse(ThreadContext context, IRubyObject self, IRubyObject[] args) {
+            return context.tru;
+        }
+
+        // jruby/jruby#7851: Restore automatic arity checking with an opt-out
+        @JRubyMethod(required = 1, optional = 1)
+        public static IRubyObject optWithCheckArityDefault(ThreadContext context, IRubyObject self, IRubyObject[] args) {
+            return context.tru;
+        }
     }
 
     public static class GH3463Module {