Hacked in double instance creation

src/spectator/double.cr

@@ -1,5 +1,5 @@
 module Spectator
-  module Double
+  abstract struct Double
     macro stub(definition)
       def {{definition.name.id}}
         {{definition.block.body}}

src/spectator/dsl/builder.cr

@@ -101,6 +101,11 @@ module Spectator::DSL
       current_group.add_post_condition(block)
     end
 
+    def add_double(id : Symbol, double_type : Double.class) : Nil
+      double_factory = DoubleFactory.new(double_type)
+      current_group.add_double(id, double_factory)
+    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

src/spectator/dsl/double_factory.cr

@@ -0,0 +1,17 @@
+require "../double"
+
+module Spectator::DSL
+  # Creates instances of doubles from a specified type.
+  class DoubleFactory
+    # Creates the factory.
+    # The type passed to this constructor must be a double.
+    def initialize(@double_type : Double.class)
+    end
+
+    # Constructs a new double instance and returns it.
+    # The *sample_values* are passed to `Double#initialize`.
+    def build(sample_values : Internals::SampleValues) : Double
+      @double_type.new
+    end
+  end
+end

src/spectator/dsl/example_group_builder.cr

@@ -7,6 +7,8 @@ module Spectator::DSL
     # and the root example group can't be a child.
     alias Child = ExampleFactory | NestedExampleGroupBuilder
 
+    private getter doubles = {} of Symbol => DoubleFactory
+
     # Factories and builders for all examples and groups.
     @children = [] of Child
 
@@ -63,6 +65,10 @@ module Spectator::DSL
       @post_conditions << block
     end
 
+    def add_double(id : Symbol, double_factory : DoubleFactory) : Nil
+      @doubles[id] = double_factory
+    end
+
     # Constructs an `ExampleHooks` instance with all the hooks defined for this group.
     # This method should be called only when the group is being built,
     # otherwise some hooks may be missing.

src/spectator/dsl/nested_example_group_builder.cr

@@ -26,7 +26,7 @@ module Spectator::DSL
     # The *parent* should be the group that contains this group.
     # The *sample_values* will be given to all of the examples (and groups) nested in this group.
     def build(parent : ExampleGroup, sample_values : Internals::SampleValues) : NestedExampleGroup
-      NestedExampleGroup.new(@what, parent, hooks, conditions).tap do |group|
+      NestedExampleGroup.new(@what, parent, hooks, conditions, doubles).tap do |group|
         # Set the group's children to built versions of the children from this instance.
         group.children = @children.map do |child|
           # Build the child and up-cast to prevent type errors.

src/spectator/dsl/root_example_group_builder.cr

@@ -6,7 +6,7 @@ module Spectator::DSL
     # Creates a `RootExampleGroup` which can have instances of `Example` and `ExampleGroup` nested in it.
     # The *sample_values* will be given to all of the examples (and groups) nested in this group.
     def build(sample_values : Internals::SampleValues) : RootExampleGroup
-      RootExampleGroup.new(hooks, conditions).tap do |group|
+      RootExampleGroup.new(hooks, conditions, doubles).tap do |group|
         # Set the group's children to built versions of the children from this instance.
         group.children = @children.map do |child|
           # Build the child and up-cast to prevent type errors.

src/spectator/dsl/sample_example_group_builder.cr

@@ -43,7 +43,7 @@ module Spectator::DSL
 
       # This creates the container for the sub-groups.
       # The hooks are defined here, instead of repeating for each sub-group.
-      NestedExampleGroup.new(@what, parent, hooks, conditions).tap do |group|
+      NestedExampleGroup.new(@what, parent, hooks, conditions, doubles).tap do |group|
         # Set the container group's children to be sub-groups for each item in the collection.
         group.children = collection.map do |value|
           # Create a sub-group for each item in the collection.
@@ -61,7 +61,7 @@ module Spectator::DSL
     private def build_sub_group(parent : ExampleGroup, sample_values : Internals::SampleValues, value : T) : NestedExampleGroup
       # Add the value to sample values for this sub-group.
       sub_values = sample_values.add(@symbol, @name, value)
-      NestedExampleGroup.new(value.to_s, parent, ExampleHooks.empty, ExampleConditions.empty).tap do |group|
+      NestedExampleGroup.new(value.to_s, parent, ExampleHooks.empty, ExampleConditions.empty, {} of Symbol => DoubleFactory).tap do |group|
         # Set the sub-group's children to built versions of the children from this instance.
         group.children = @children.map do |child|
           # Build the child and up-cast to prevent type errors.

src/spectator/dsl/structure_dsl.cr

@@ -1440,15 +1440,15 @@ module Spectator::DSL
     macro double(name, &block)
       {% if block.is_a?(Nop) %}
         # Create an instance of the double.
-        Double{{name.id}}.new
+        ::Spectator::Internals::Harness.current.double({{name.id.symbolize}}).as(Double{{name.id}})
       {% else %}
         # Define a double.
-        struct Double{{name.id}} # TODO: Use fresh variable %double
-          include ::Spectator::Double
+        struct Double{{name.id}} < ::Spectator::Double # TODO: Use fresh variable %double
+          #include {{@type.id}} # Include parent type to allow contextual methods in the double.
 
           {{block.body}}
         end
-        # TODO: Register double in current context.
+        ::Spectator::DSL::Builder.add_double({{name.id.symbolize}}, Double{{name.id}})
       {% end %}
       {% debug %}
     end

src/spectator/example.cr

@@ -16,6 +16,8 @@ module Spectator
     # Source where the example originated from.
     abstract def source : Source
 
+    protected getter sample_values : Internals::SampleValues
+
     # Runs the example code.
     # A result is returned, which represents the outcome of the test.
     # An example can be run only once.
@@ -32,7 +34,7 @@ module Spectator
     # Creates the base of the example.
     # The group should be the example group the example belongs to.
     # The *sample_values* are passed to the example code.
-    def initialize(@group, sample_values : Internals::SampleValues)
+    def initialize(@group, @sample_values)
     end
 
     # Indicates there is only one example to run.

src/spectator/example_group.cr

@@ -17,7 +17,7 @@ module Spectator
 
     # Creates the example group.
     # The hooks are stored to be triggered later.
-    def initialize(@hooks : ExampleHooks, @conditions : ExampleConditions)
+    def initialize(@hooks : ExampleHooks, @conditions : ExampleConditions, @doubles : Hash(Symbol, DSL::DoubleFactory))
       @before_all_hooks_run = false
       @after_all_hooks_run = false
     end
@@ -40,6 +40,10 @@ module Spectator
       @example_count = children.sum(&.example_count)
     end
 
+    def double(id, sample_values)
+      @doubles[id].build(sample_values)
+    end
+
     # Yields each direct descendant.
     def each
       children.each do |child|

src/spectator/internals/harness.cr

@@ -46,6 +46,10 @@ module Spectator::Internals
       @reporter.expectations
     end
 
+    def double(id)
+      example.group.double(id, example.sample_values)
+    end
+
     # Creates a new harness.
     # The example the harness is for should be passed in.
     private def initialize(@example)

src/spectator/nested_example_group.cr

@@ -18,8 +18,8 @@ module Spectator
     # The parent's children must contain this group,
     # otherwise there may be unexpected behavior.
     # The *hooks* are stored to be triggered later.
-    def initialize(@what, @parent, hooks : ExampleHooks, conditions : ExampleConditions)
-      super(hooks, conditions)
+    def initialize(@what, @parent, hooks : ExampleHooks, conditions : ExampleConditions, doubles : Hash(Symbol, DSL::DoubleFactory))
+      super(hooks, conditions, doubles)
     end
 
     # Indicates wheter the group references a type.