Move stack handling to its own type

src/spectator/builders/example_group_stack.cr

@@ -0,0 +1,22 @@
+module Spectator::Builders
+  struct ExampleGroupStack
+    getter root = RootExampleGroupBuilder.new
+
+    @stack = Deque(ExampleGroupBuilder).new(1, @root)
+
+    def current
+      @stack.last
+    end
+
+    def push(group : NestedExampleGroupBuilder)
+      current.add_child(group)
+      @stack.push(group)
+    end
+
+    def pop
+      raise "Attempted to pop root example group from stack" if current == root
+
+      @stack.pop
+    end
+  end
+end

src/spectator/dsl/builder.cr

@@ -6,26 +6,7 @@ module Spectator::DSL
   module Builder
     extend self
 
-    # Root group that contains all examples and groups in the spec.
+    @@stack = Builders::ExampleGroupStack.new
-    private class_getter root_group = RootExampleGroupBuilder.new
-
-    # Stack for tracking the current group the spec is working in.
-    # The last item (top of the stack) is the current group.
-    # The first item (bottom of the stack) is the root group (`#root_group`).
-    # The root group should never be popped.
-    @@group_stack = Array(ExampleGroupBuilder).new(1, root_group)
-
-    # Retrieves the current group the spec is working in.
-    private def current_group
-      @@group_stack.last
-    end
-
-    # Adds a new group to the stack.
-    # Calling this method indicates the spec has entered a nested group.
-    private def push_group(group : NestedExampleGroupBuilder)
-      current_group.add_child(group)
-      @@group_stack.push(group)
-    end
 
     # Begins a new nested group in the spec.
     # A corresponding `#end_group` call must be made
@@ -34,7 +15,7 @@ module Spectator::DSL
     # as arguments to this method are passed directly to it.
     def start_group(*args) : Nil
       group = NestedExampleGroupBuilder.new(*args)
-      push_group(group)
+      @@stack.push(group)
     end
 
     # Begins a new sample group in the spec -
@@ -45,7 +26,7 @@ module Spectator::DSL
     # as arguments to this method are passed directly to it.
     def start_sample_group(*args) : Nil
       group = SampleExampleGroupBuilder.new(*args)
-      push_group(group)
+      @@stack.push(group)
     end
 
     # Marks the end of a group in the spec.
@@ -53,58 +34,61 @@ module Spectator::DSL
     # It is also important to line up the start and end calls.
     # Otherwise examples might get placed into wrong groups.
     def end_group : Nil
-      @@group_stack.pop
+      @@stack.pop
     end
 
     # Adds an example type to the current group.
     # The class name of the example should be passed as an argument.
     # The example will be instantiated later.
-    def add_example(example_type : Example.class) : Nil
+    def add_example(description : String, source : Source,
-      factory = ExampleFactory.new(example_type)
+      example_type : ::SpectatorTest.class, &runner : ::SpectatorTest ->) : Nil
-      current_group.add_child(factory)
+      builder = ->{ example_type.new.as(::SpectatorTest) }
+      wrapper = TestWrapper.new(description, source, builder, runner)
+      example = Example.new(current_group, wrapper)
+      # TODO: Add to stack.
     end
 
     # Adds a block of code to run before all examples in the current group.
     def add_before_all_hook(&block : ->) : Nil
-      current_group.add_before_all_hook(block)
+      @@stack.current.add_before_all_hook(block)
     end
 
     # Adds a block of code to run before each example in the current group.
     def add_before_each_hook(&block : ->) : Nil
-      current_group.add_before_each_hook(block)
+      @@stack.current.add_before_each_hook(block)
     end
 
     # Adds a block of code to run after all examples in the current group.
     def add_after_all_hook(&block : ->) : Nil
-      current_group.add_after_all_hook(block)
+      @@stack.current.add_after_all_hook(block)
     end
 
     # Adds a block of code to run after each example in the current group.
     def add_after_each_hook(&block : ->) : Nil
-      current_group.add_after_each_hook(block)
+      @@stack.current.add_after_each_hook(block)
     end
 
     # Adds a block of code to run before and after each example in the current group.
     # The block of code will be given another proc as an argument.
     # It is expected that the block will call the proc.
     def add_around_each_hook(&block : Proc(Nil) ->) : Nil
-      current_group.add_around_each_hook(block)
+      @@stack.current.add_around_each_hook(block)
     end
 
     # Adds a pre-condition to run at the start of every example in the current group.
     def add_pre_condition(&block : ->) : Nil
-      current_group.add_pre_condition(block)
+      @@stack.current.add_pre_condition(block)
     end
 
     # Adds a post-condition to run at the end of every example in the current group.
     def add_post_condition(&block : ->) : Nil
-      current_group.add_post_condition(block)
+      @@stack.current.add_post_condition(block)
     end
 
     # Builds the entire spec and returns it as a test suite.
     # This should be called only once after the entire spec has been defined.
     protected def build(filter : ExampleFilter) : TestSuite
-      group = root_group.build(Internals::SampleValues.empty)
+      group = @@stack.root.build(Internals::SampleValues.empty)
       TestSuite.new(group, filter)
     end
   end