Handle have_ prefix for matcher

src/spectator/dsl/matcher_dsl.cr

@@ -561,7 +561,7 @@ module Spectator::DSL
     end
 
     # Used to create predicate matchers.
-    # Any missing method that starts with 'be_' will be handled.
+    # Any missing method that starts with 'be_' or 'have_' will be handled.
     # All other method names will be ignored and raise a compile-time error.
     #
     # This can be used to simply check a predicate method that ends in '?'.
@@ -570,10 +570,22 @@ module Spectator::DSL
     # expect("foobar").to be_ascii_only
     # # Is equivalent to:
     # expect("foobar".ascii_only?).to be_true
+    #
+    # expect("foobar").to_not have_back_references
+    # # Is equivalent to:
+    # expect("foobar".has_back_references?).to_not be_true
     # ```
     macro method_missing(call)
       {% if call.name.starts_with?("be_") %}
-        {% method_name = call.name[3..-1] %} # Remove be_ prefix.
+        # Remove `be_` prefix.
+        {% method_name = call.name[3..-1] %}
+      {% elsif call.name.starts_with?("have_") %}
+        # Swap `have_` with `has_`.
+        {% method_name = ("has_" + call.name[5..-1].stringify).id %}
+      {% else %}
+        {% raise "Undefined local variable or method '#{call}'" %}
+      {% end %}
+
       descriptor = { {{method_name}}: Tuple.new({{call.args.splat}}) }
       label = String::Builder.new({{method_name.stringify}})
       {% unless call.args.empty? %}
@@ -587,9 +599,6 @@ module Spectator::DSL
         label << ')'
       {% end %}
       ::Spectator::Matchers::PredicateMatcher.new(descriptor, label.to_s)
-      {% else %}
-        {% raise "Undefined local variable or method '#{call}'" %}
-      {% end %}
     end
   end
 end