Implement random test order execution

src/spectator/command_line_arguments_config_source.cr

@@ -21,8 +21,9 @@ module Spectator
         parser.on("-e", "--example STRING", "Run examples whose full nested names include STRING") { |pattern| raise NotImplementedError.new("-e") }
         parser.on("-l", "--line LINE", "Run examples whose line matches LINE") { |line| raise NotImplementedError.new("-l") }
         parser.on("-p", "--profile", "Display the 10 slowest specs") { raise NotImplementedError.new("-p") }
+        parser.on("-r", "--rand", "Randomize the execution order of tests") { builder.randomize }
+        parser.on("--seed INTEGER", "Set the seed for the random number generator (implies -r)") { |seed| builder.randomize; builder.seed = seed.to_i }
         parser.on("--location FILE:LINE", "Run the example at line 'LINE' in the file 'FILE', multiple allowed") { |location| raise NotImplementedError.new("--location") }
-        parser.on("--seed INTEGER", "Set the seed for the random number generator") { |seed| builder.seed = seed.to_i }
         parser.on("--json", "Generate JSON output") { builder.formatter = Formatting::JsonFormatter.new }
         parser.on("--junit_output OUTPUT_DIR", "Generate JUnit XML output") { |output_dir| builder.add_formatter(Formatting::JUnitFormatter.new(output_dir)) }
         parser.on("--tap", "Generate TAP output (Test Anything Protocol)") { builder.formatter = Formatting::TAPFormatter.new }

src/spectator/config.cr

@@ -16,6 +16,9 @@ module Spectator
     # Random number generator to use for everything.
     getter random : Random
 
+    # Indicates whether tests are run in a random order.
+    getter? randomize : Bool
+
     # Creates a new configuration.
     def initialize(builder)
       @formatters = builder.formatters
@@ -23,6 +26,7 @@ module Spectator
       @fail_blank = builder.fail_blank?
       @dry_run = builder.dry_run?
       @random = builder.random
+      @randomize = builder.randomize?
     end
 
     # Yields each formatter that should be reported to.

src/spectator/config_builder.cr

@@ -16,6 +16,7 @@ module Spectator
     @fail_fast = false
     @fail_blank = false
     @dry_run = false
+    @randomize = false
 
     # Sets the primary formatter to use for reporting test progress and results.
     def formatter=(formatter : Formatting::Formatter)
@@ -91,6 +92,22 @@ module Spectator
     def seed=(seed)
       @random = Random.new(seed)
     end
+
+    # Randomizes test execution order.
+    def randomize
+      self.randomize = true
+    end
+
+    # Enables or disables running tests in a random order.
+    def randomize=(flag)
+      @randomize = flag
+    end
+
+    # Indicates whether tests are run in a random order.
+    def randomize?
+      @randomize
+    end
+
     # Creates a configuration.
     def build : Config
       Config.new(self)

src/spectator/runner.cr

@@ -31,13 +31,24 @@ module Spectator
 
     # Runs all examples and adds results to a list.
     private def collect_results(results)
-      @suite.each do |example|
+      example_order.each do |example|
         result = run_example(example).as(Result)
         results << result
         break if @config.fail_fast? && result.is_a?(FailedResult)
       end
     end
 
+    # Retrieves an enumerable for the examples to run.
+    # The order of examples is randomized
+    # if specified by the configuration.
+    private def example_order
+      if @config.randomize?
+        @suite.to_a.shuffle(@config.random)
+      else
+        @suite.each
+      end
+    end
+
     # Runs a single example and returns the result.
     # The formatter is given the example and result information.
     private def run_example(example)