Add example filter to config

src/spectator/config.cr

@@ -19,6 +19,9 @@ module Spectator
     # Indicates whether tests are run in a random order.
     getter? randomize : Bool
 
+    # Filter that determines which examples to run.
+    getter example_filter : ExampleFilter
+
     # Creates a new configuration.
     def initialize(builder)
       @formatters = builder.formatters
@@ -27,6 +30,7 @@ module Spectator
       @dry_run = builder.dry_run?
       @random = builder.random
       @randomize = builder.randomize?
+      @example_filter = builder.example_filter
     end
 
     # Yields each formatter that should be reported to.

src/spectator/config_builder.cr

@@ -17,6 +17,7 @@ module Spectator
     @fail_blank = false
     @dry_run = false
     @randomize = false
+    @filters = [] of ExampleFilter
 
     # Sets the primary formatter to use for reporting test progress and results.
     def formatter=(formatter : Formatting::Formatter)
@@ -108,6 +109,22 @@ module Spectator
       @randomize
     end
 
+    # Adds a filter to determine which examples can run.
+    def add_example_filter(filter : ExampleFilter)
+      @filters << filter
+    end
+
+    # Retrieves a filter that determines which examples can run.
+    # If no filters were added with `#add_example_filter`,
+    # then the returned filter will allow all examples to be run.
+    protected def example_filter
+      if @filters.empty?
+        NullExampleFilter.new
+      else
+        CompositeExampleFilter.new(@filters)
+      end
+    end
+
     # Creates a configuration.
     def build : Config
       Config.new(self)