Check for and allow expected exits

src/spectator/mocks/registry.cr

@@ -70,6 +70,14 @@ module Spectator::Mocks
         fetch_type(object.class).expected.any?(&.callable?(call))
     end
 
+    def exit_handled? : Bool
+      # Lazily check if an `exit` method was called and it was expected.
+      # This is okay since an `expect().to receive(:exit)` should check the details of the call.
+      (@entries.any? { |_key, entry| entry.expected.any? { |stub| stub.name == :exit } } ||
+        @all_instances.any? { |_key, entry| entry.expected.any? { |stub| stub.name == :exit } }) &&
+        @entries.any? { |_key, entry| entry.calls.any? { |call| call.name == :exit } }
+    end
+
     def expect(object, stub : MethodStub) : Nil
       fetch_instance(object).expected.add(stub)
     end

src/spectator/runnable_example.cr

@@ -21,6 +21,7 @@ module Spectator
         run_example(result)
         @finished = true
         context.run_after_hooks(self)
+        result.error = nil if result.error.is_a?(SystemExit) && Harness.current.mocks.exit_handled?
         run_deferred(result) unless result.error
       end
     end