From 165178237c9e2af53b6c0ab8f44fbca4310d34af Mon Sep 17 00:00:00 2001
From: Michael Miller <icy.arctic.fox@gmail.com>
Date: Fri, 22 Mar 2019 13:34:44 -0600
Subject: [PATCH] Add dummy match data

Apparently the abstract bug pops up again when there are no tests.
---
 src/spectator/matchers/dummy_match_data.cr | 32 ++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 src/spectator/matchers/dummy_match_data.cr

diff --git a/src/spectator/matchers/dummy_match_data.cr b/src/spectator/matchers/dummy_match_data.cr
new file mode 100644
index 0000000..175cf53
--- /dev/null
+++ b/src/spectator/matchers/dummy_match_data.cr
@@ -0,0 +1,32 @@
+module Spectator::Matchers
+  # Match data that does nothing.
+  # This is to workaround a Crystal compiler bug.
+  # See: [Issue 4225](https://github.com/crystal-lang/crystal/issues/4225)
+  # If there are no concrete implementations of an abstract class,
+  # the compiler gives an error.
+  # The error indicates an abstract method is undefined.
+  # This class shouldn't be used, it's just to trick the compiler.
+  private struct DummyMatchData < MatchData
+    # Creates the match data.
+    def initialize
+      super(false)
+    end
+
+    # Dummy values.
+    def named_tuple
+      {
+        you: "shouldn't be calling this."
+      }
+    end
+
+    # Dummy message.
+    def message
+      "You shouldn't be calling this."
+    end
+
+    # Dummy message
+    def negated_message
+      "You shouldn't be calling this."
+    end
+  end
+end