Create ExampleGroup and use shared ExampleNode type

src/spectator/example_base.cr

@@ -1,52 +1,9 @@
-require "./example_group"
+require "./example_node"
 require "./result"
-require "./source"
 
 module Spectator
   # Common base type for all examples.
-  abstract class ExampleBase
+  abstract class ExampleBase < ExampleNode
-    # Location of the example in source code.
-    getter! source : Source
-
-    # User-provided name or description of the test.
-    # This does not include the group name or descriptions.
-    # Use `#to_s` to get the full name.
-    #
-    # This value will be nil if no name was provided.
-    # In this case, the name should be set
-    # to the description of the first matcher that runs in the example.
-    #
-    # If this value is a `Symbol`, the user specified a type for the name.
-    getter! name : String | Symbol
-
-    # Group the example belongs to.
-    # Hooks are used from this group.
-    getter! group : ExampleGroup
-
-    # Assigns the group the example belongs to.
-    # If the example already belongs to a group,
-    # it will be removed from the previous group before adding it to the new group.
-    def group=(group : ExampleGroup?)
-      if (previous = @group)
-        previous.remove_example(self)
-      end
-      group.add_example(self) if group
-      @group = group
-    end
-
-    # Creates the base of the example.
-    # The *name* describes the purpose of the example.
-    # It can be a `Symbol` to describe a type.
-    # The *source* tracks where the example exists in source code.
-    # The example will be assigned to *group* if it is provided.
-    def initialize(@name : String | Symbol? = nil, @source : Source? = nil, group : ExampleGroup? = nil)
-      # Ensure group is linked.
-      self.group = group
-    end
-
-    # Indicates whether the example already ran.
-    abstract def finished? : Bool
-
     # Retrieves the result of the last time the example ran.
     # This will be nil if the example hasn't run,
     # and should not be nil if it has.
@@ -58,25 +15,6 @@ module Spectator
       result? || raise(NilAssertionError("Example has no result"))
     end
 
-    # Constructs the full name or description of the example.
-    # This prepends names of groups this example is part of.
-    def to_s(io)
-      name = @name
-
-      # Prefix with group's full name if the example belongs to a group.
-      if (group = @group)
-        group.to_s(io)
-
-        # Add padding between the group name and example name,
-        # only if the names appear to be symbolic.
-        if group.name.is_a?(Symbol) && name.is_a?(String)
-          io << ' ' unless name.starts_with?('#') || name.starts_with?('.')
-        end
-      end
-
-      name.to_s(io)
-    end
-
     # Exposes information about the example useful for debugging.
     def inspect(io)
       raise NotImplementedError.new("#inspect")

src/spectator/example_group.cr

@@ -0,0 +1,38 @@
+module Spectator
+  # Collection of examples and sub-groups.
+  class ExampleGroup < ExampleNode
+    include Enumerable(ExampleNode)
+
+    @nodes = [] of ExampleNode
+
+    # Removes the specified *node* from the group.
+    # The node will be unassigned from this group.
+    def delete(node : ExampleNode)
+      # Only remove from the group if it is associated with this group.
+      return unless node.group == self
+
+      node.group = nil
+      @nodes.delete(node)
+    end
+
+    # Yields each node (example and sub-group).
+    def each
+      @nodes.each { |node| yield node }
+    end
+
+    # Adds the specified *node* to the group.
+    # Assigns the node to this group.
+    # If the node already belongs to a group,
+    # it will be removed from the previous group before adding it to this group.
+    def <<(node : ExampleNode)
+      # Remove from existing group if the node is part of one.
+      if (previous = node.group?)
+        previous.delete(node)
+      end
+
+      # Add the node to this group and associate with it.
+      @nodes << node
+      node.group = self
+    end
+  end
+end

src/spectator/example_node.cr

@@ -0,0 +1,64 @@
+require "./source"
+
+module Spectator
+  # A single example or collection (group) of examples in an example tree.
+  abstract class ExampleNode
+    # Location of the node in source code.
+    getter! source : Source
+
+    # User-provided name or description of the test.
+    # This does not include the group name or descriptions.
+    # Use `#to_s` to get the full name.
+    #
+    # This value will be nil if no name was provided.
+    # In this case, and the node is a runnable example,
+    # the name should be set to the description
+    # of the first matcher that runs in the test case.
+    #
+    # If this value is a `Symbol`, the user specified a type for the name.
+    getter! name : String | Symbol
+
+    # Updates the name of the node.
+    protected def name=(@name : String)
+    end
+
+    # Group the node belongs to.
+    getter! group : ExampleGroup
+
+    # Assigns the node to the specified *group*.
+    # This is an internal method and should only be called from `ExampleGroup`.
+    # `ExampleGroup` manages the association of nodes to groups.
+    protected setter group : ExampleGroup?
+
+    # Creates the node.
+    # The *name* describes the purpose of the node.
+    # It can be a `Symbol` to describe a type.
+    # The *source* tracks where the node exists in source code.
+    # The node will be assigned to *group* if it is provided.
+    def initialize(@name : String | Symbol? = nil, @source : Source? = nil, group : ExampleGroup? = nil)
+      # Ensure group is linked.
+      group << self if group
+    end
+
+    # Indicates whether the node has completed.
+    abstract def finished? : Bool
+
+    # Constructs the full name or description of the node.
+    # This prepends names of groups this node is part of.
+    def to_s(io)
+      name = @name
+
+      # Prefix with group's full name if the node belongs to a group.
+      if (group = @group)
+        io << group
+
+        # Add padding between the node names
+        # only if the names don't appear to be symbolic.
+        io << ' ' unless group.name.is_a?(Symbol) && name.is_a?(String) &&
+                         (name.starts_with?('#') || name.starts_with?('.'))
+      end
+
+      io << name
+    end
+  end
+end