Add specialized should/should_not methods for procs

src/spectator/should.cr

@@ -30,3 +30,17 @@ class Object
     ::Spectator::Expectations::ValueExpectationPartial.new(self, __FILE__, __LINE__).to_not(matcher)
   end
 end
+
+struct Proc(*T, R)
+  # Extension method to create an expectation for a block of code (proc).
+  # Depending on the matcher, the proc may be executed multiple times.
+  def should(matcher : ::Spectator::Matchers::Matcher)
+    ::Spectator::Expectations::BlockExpectationPartial.new(self, __FILE__, __LINE__).to(matcher)
+  end
+
+  # Works the same as `#should` except the condition is inverted.
+  # When `#should` succeeds, this method will fail, and vice-versa.
+  def should_not(matcher : ::Spectator::Matchers::Matcher)
+    ::Spectator::Expectations::BlockExpectationPartial.new(self, __FILE__, __LINE__).to_not(matcher)
+  end
+end