1 files changed, 156 insertions, 0 deletions
diff --git a/t/roles/overloading_composition_errors.t b/t/roles/overloading_composition_errors.t
new file mode 100644
index 0000000..75e79ca
--- /dev/null
+++ b/t/roles/overloading_composition_errors.t
@@ -0,0 +1,156 @@
+use strict;
+use warnings;
+
+use Test::More 0.88;
+use Test::Fatal;
+use Test::Warnings;
+
+use lib 't/lib';
+
+{
+    package Role::HasFallback;
+    use Moose::Role;
+
+    use overload
+        q{""}    => '_stringify',
+        fallback => 1;
+
+    sub _stringify { __PACKAGE__ }
+}
+
+{
+    package Role::NoFallback;
+    use Moose::Role;
+
+    use overload
+        '0+'    => '_numify',
+        fallback => 0;
+
+    sub _numify { 42 }
+}
+
+{
+    package Class1;
+    use Moose;
+    ::like(
+        ::exception { with qw( Role::HasFallback Role::NoFallback ) },
+        qr/\QWe have encountered an overloading conflict for the fallback during composition. This is a fatal error./,
+        'exception from fallback conflict during role summation'
+    );
+}
+
+{
+    package Role::NoOverloading;
+    use Moose::Role;
+
+    sub foo { 42 }
+}
+
+{
+    package Class2;
+    use Moose;
+    ::like(
+        ::exception { with qw( Role::HasFallback Role::NoFallback Role::NoOverloading ) },
+        qr/\QWe have encountered an overloading conflict for the fallback during composition. This is a fatal error./,
+        'exception from fallback conflict during role summation including role without overloading'
+    );
+}
+
+{
+    package Role::StringifiesViaSubref1;
+    use Moose::Role;
+
+    use overload q{""} => sub { 'foo' };
+}
+
+{
+    package Role::StringifiesViaSubref2;
+    use Moose::Role;
+
+    use overload q{""} => sub { 'bar' };
+}
+
+{
+    package Class3;
+    use Moose;
+    ::like(
+        ::exception { with qw( Role::StringifiesViaSubref1 Role::StringifiesViaSubref2 ) },
+        qr/\QThe two roles both overload the '""' operator. This is a fatal error./,
+        'exception when two roles with different subref overloading conflict during role summation'
+    );
+}
+
+{
+    package Class4;
+    use Moose;
+    ::like(
+        ::exception { with qw( Role::StringifiesViaSubref1 Role::StringifiesViaSubref2 Role::NoOverloading ) },
+        qr/\QThe two roles both overload the '""' operator. This is a fatal error./,
+        'exception when two roles with different subref overloading conflict during role summation including role without overloading'
+    );
+}
+
+{
+    package Role::StringifiesViaMethod1;
+    use Moose::Role;
+
+    use overload q{""} => '_stringify1';
+    sub _stringify1 { 'foo' }
+}
+
+{
+    package Role::StringifiesViaMethod2;
+    use Moose::Role;
+
+    use overload q{""} => '_stringify2';
+    sub _stringify2 { 'foo' }
+}
+
+{
+    package Class5;
+    use Moose;
+    ::like(
+        ::exception { with qw( Role::StringifiesViaMethod1 Role::StringifiesViaMethod2 ) },
+        qr/\QThe two roles both overload the '""' operator. This is a fatal error./,
+        'exception when two roles with different method overloading conflict during role summation'
+    );
+}
+
+{
+    package Class6;
+    use Moose;
+    ::like(
+        ::exception { with qw( Role::StringifiesViaMethod1 Role::StringifiesViaMethod2 Role::NoOverloading ) },
+        qr/\QThe two roles both overload the '""' operator. This is a fatal error./,
+        'exception when two roles with different method overloading conflict during role summation including role without overloading'
+    );
+}
+
+{
+    {
+        package R1;
+        use Moose::Role;
+
+        use overload '&{}' => 'as_code';
+
+        sub as_code { }
+    }
+
+    {
+        package R2;
+        use Moose::Role;
+        with 'R1';
+    }
+
+    {
+        package C1;
+        use Moose;
+        ::is(
+            ::exception { with 'R1', 'R2' },
+            undef,
+            'no conflict when class consumes multiple roles with the same overloading'
+        );
+    }
+}
+
+done_testing();