Flag to disable running tests

This is needed for testing Spectator.

spec/spec_helper.cr

@@ -1,2 +1,5 @@
 require "spec"
 require "../src/spectator"
+
+# Prevent Spectator from trying to run tests.
+Spectator.autorun = false

src/spectator.cr

@@ -45,7 +45,14 @@ module Spectator
     end
   end
 
+  # Flag indicating whether Spectator should automatically run tests.
+  # This should be left alone (set to true) in typical usage.
+  # There are times when Spectator shouldn't run tests.
+  # One of those is testing Spectator.
+  class_property? autorun = true
+
   # All tests are ran just before the executable exits.
+  # Tests will be skipped, however, if `#autorun?` is set to false.
   # There are a couple of reasons for this.
   #
   # First is that we want a clean interface for the end-user.
@@ -62,7 +69,11 @@ module Spectator
   # Crystal doesn't display much information about what happened.
   # That issue is handled by putting a begin/rescue block to show a custom error message.
   at_exit do
-    begin
+    run if autorun?
+  end
+
+  # Builds the tests and runs the framework.
+  private def self.run
     # Build the root-level example group and run it.
     group = ::Spectator::DSL::Builder.build
     Runner.new(group).run
@@ -78,5 +89,4 @@ module Spectator
     puts ex.backtrace.join("\n")
     exit(1)
   end
-  end
 end