Pass along class type instead of collection

src/spectator/dsl/builder.cr

@@ -41,10 +41,10 @@ module Spectator::DSL
     # that is, a group defined by the `StructureDSL#sample` macro in the DSL.
     # A corresponding `#end_group` call must be made
     # when the group being started is finished.
-    # See `SampleExampleGroupBuilder#initialize` for the arguments
+    # See `SampleExampleGroupBuilder#create` for the arguments
     # as arguments to this method are passed directly to it.
     def start_sample_group(*args) : Nil
-      group = SampleExampleGroupBuilder.new(*args)
+      group = SampleExampleGroupBuilder.create(*args)
       push_group(group)
     end
 

src/spectator/dsl/sample_example_group_builder.cr

@@ -29,6 +29,11 @@ module Spectator::DSL
       super(what)
     end
 
+    def self.create(what, collection_type : C.class, name, symbol) forall C
+      collection = collection_type.new(sample_values).to_a
+      SampleExampleGroupBuilder.new(what, collection, name, symbol)
+    end
+
     # Builds the example group.
     # A new `NestedExampleGroup` will be returned
     # which can have instances of `Example` and `ExampleGroup` nested in it.

src/spectator/dsl/structure_dsl.cr

@@ -558,7 +558,7 @@ module Spectator::DSL
         # Sample groups require additional configuration.
         ::Spectator::DSL::Builder.start_sample_group(
           {{collection.stringify}}, # String representation of the collection.
-          Sample%sample.new.%to_a,  # All elements in the collection.
+          Sample%sample,            # All elements in the collection.
           {{name.stringify}},       # Name for the current element.
           :%sample                  # Unique identifier for retrieving elements for the associated collection.
         )
@@ -678,7 +678,7 @@ module Spectator::DSL
         # Sample groups require additional configuration.
         ::Spectator::DSL::Builder.start_sample_group(
           {{collection.stringify}}, # String representation of the collection.
-          Sample%sample.new.%to_a,  # All elements in the collection.
+          Sample%sample,            # All elements in the collection.
           {{name.stringify}},       # Name for the current element.
           :%sample                  # Unique identifier for retrieving elements for the associated collection.
         )