Add crystal spec --list-tags

src/spec.cr

@@ -103,6 +103,8 @@ def Spec.configure_formatter(formatter, output_path = nil)
   when "junit"
     junit_formatter = Spec::JUnitFormatter.file(Path.new(output_path.not_nil!))
     Spec.add_formatter(junit_formatter)
+  when "list_tags"
+    Spec.override_default_formatter(Spec::ListTagsFormatter.new)
   when "verbose"
     Spec.override_default_formatter(Spec::VerboseFormatter.new)
   when "tap"

src/spec/cli.cr

@@ -19,6 +19,9 @@ module Spec
   # :nodoc:
   class_property? focus = false
 
+  # :nodoc:
+  class_property? list_tags = false
+
   # :nodoc:
   def self.add_location(file, line)
     locations = @@locations ||= {} of String => Array(Int32)
@@ -84,6 +87,10 @@ module Spec
       opts.on("--tag TAG", "run examples with the specified TAG, or exclude examples by adding ~ before the TAG.") do |tag|
         Spec.add_tag tag
       end
+      opts.on("--list-tags", "lists all the tags used.") do
+        Spec.list_tags = true
+        configure_formatter("list_tags")
+      end
       opts.on("--order MODE", "run examples in random order by passing MODE as 'random' or to a specific seed by passing MODE as the seed value") do |mode|
         if mode.in?("default", "random")
           Spec.order = mode

src/spec/context.cr

@@ -5,6 +5,7 @@ module Spec
   abstract class Context
     # All the children, which can be `describe`/`context` or `it`
     getter children = [] of ExampleGroup | Example
+    getter tag_counts = Hash(String, Int32).new(0)
 
     def randomize(randomizer)
       children.each do |child|
@@ -180,8 +181,14 @@ module Spec
     end
 
     def print_results(elapsed_time, aborted = false)
+      if Spec.list_tags?
+        longest_name = tag_counts.keys.map { |tag_name| tag_name.size }.max
+        tag_counts.to_a.sort_by { |k, v| -v }.each do |tag_name, count|
+          puts "#{tag_name.rjust(longest_name)}: #{count}"
+        end
+      end
       pendings = results_for(:pending)
-      unless pendings.empty?
+      unless pendings.empty? || Spec.list_tags?
         puts
         puts "Pending:"
         pendings.each do |pending|

src/spec/example.cr

@@ -29,8 +29,22 @@ module Spec
         non_nil_block = block
         start = Time.monotonic
 
-        ran = @parent.run_around_each_hooks(Example::Procsy.new(self) { internal_run(start, non_nil_block) })
-        ran || internal_run(start, non_nil_block)
+        if Spec.list_tags?
+          tags = all_tags
+          tags << "untagged" if tags.empty?
+          context = self.parent
+          while !context.nil?
+            tags.each do |tag|
+              context.tag_counts[tag] += 1
+            end
+            break if !context.responds_to?(:parent)
+            context = context.parent
+          end
+          @parent.report(:success, description, file, line, Time.monotonic - start)
+        else
+          ran = @parent.run_around_each_hooks(Example::Procsy.new(self) { internal_run(start, non_nil_block) })
+          ran || internal_run(start, non_nil_block)
+        end
 
         # We do this to give a chance for signals (like CTRL+C) to be handled,
         # which currently are only handled when there's a fiber switch

src/spec/formatter.cr

@@ -115,6 +115,12 @@ module Spec
     end
   end
 
+  # :nodoc:
+  class ListTagsFormatter < DotFormatter
+    def report(result)
+    end
+  end
+
   @@formatters = [Spec::DotFormatter.new] of Spec::Formatter
 
   # :nodoc: