Clean up example randomization

src/spectator/config.cr

@@ -20,7 +20,7 @@ module Spectator
     getter? randomize : Bool
 
     # Seed used for random number generation.
-    getter! random_seed : UInt64?
+    getter random_seed : UInt64
 
     # Indicates whether timing information should be displayed.
     getter? profile : Bool
@@ -29,22 +29,50 @@ module Spectator
     getter example_filter : ExampleFilter
 
     # Creates a new configuration.
+    # Properties are pulled from *source*.
+    # Typically, *source* is a `ConfigBuilder`.
     def initialize(builder)
       @formatters = builder.formatters
       @fail_fast = builder.fail_fast?
       @fail_blank = builder.fail_blank?
       @dry_run = builder.dry_run?
       @randomize = builder.randomize?
-      @random_seed = builder.seed?
+      @random_seed = builder.seed
       @profile = builder.profile?
       @example_filter = builder.example_filter
     end
 
+    # Shuffles the items in an array using the configured random settings.
+    # If `#randomize?` is true, the *items* are shuffled and returned as a new array.
+    # Otherwise, the items are left alone and returned as-is.
+    # The array of *items* is never modified.
+    def shuffle(items)
+      return items unless randomize?
+
+      items.shuffle(random)
+    end
+
+    # Shuffles the items in an array using the configured random settings.
+    # If `#randomize?` is true, the *items* are shuffled and returned.
+    # Otherwise, the items are left alone and returned as-is.
+    # The array of *items* is modified, the items are shuffled in-place.
+    def shuffle!(items)
+      return items unless randomize?
+
+      items.shuffle!(random)
+    end
+
     # Yields each formatter that should be reported to.
     def each_formatter
       @formatters.each do |formatter|
         yield formatter
       end
     end
+
+    # Retrieves the configured random number generator.
+    # This will produce the same generator with the same seed every time.
+    private def random
+      Random.new(random_seed)
+    end
   end
 end

src/spectator/config_builder.cr

@@ -13,6 +13,9 @@ module Spectator
       new.build
     end
 
+    # Seed used for random number generation.
+    property seed : UInt64 = Random.rand(UInt64)
+
     @primary_formatter : Formatting::Formatter?
     @additional_formatters = [] of Formatting::Formatter
     @fail_fast = false
@@ -97,14 +100,6 @@ module Spectator
       @dry_run
     end
 
-    # Seed used for random number generation.
-    getter! seed : UInt64?
-
-    # Sets the seed for the random number generator.
-    def seed=(seed)
-      @seed = seed
-    end
-
     # Randomizes test execution order.
     def randomize
       self.randomize = true

src/spectator/spec.cr

@@ -16,16 +16,8 @@ module Spectator
     # Generates a list of examples to run.
     # The order of the examples are also sorted based on the configuration.
     private def examples
-      ExampleIterator.new(@root).to_a.tap do |examples|
-        if @config.randomize?
-          random = if (seed = @config.random_seed)
-            Random.new(seed)
-          else
-            Random.new
-          end
-          examples.shuffle!(random)
-        end
-      end
+      examples = ExampleIterator.new(@root).to_a
+      @config.shuffle!(examples)
     end
 
     private struct Runner