Add support for Set

lib/minitest/proptest.rb

@@ -5,6 +5,7 @@
 require 'minitest/proptest/property'
 require 'minitest/proptest/status'
 require 'minitest/proptest/version'
+require 'set'
 require 'yaml'
 
 module Minitest

lib/minitest/proptest/gen.rb

@@ -423,6 +423,21 @@ def for(*classes)
         xm.merge(ym)
       end.with_empty { {} }
 
+      generator_for(Set) do |x|
+        Set[x]
+      end.with_shrink_function do |f, xs|
+        list_shrink.call(f, xs.to_a)
+                   .map { |x| Set.new(x) }
+                   .uniq
+      end.with_score_function do |f, xs|
+        xs.reduce(1) do |c, x|
+          y = f.call(x).abs
+          c * (y > 0 ? y + 1 : 1)
+        end.to_i * xs.length
+      end.with_append(0, 0x10) do |xs, ys|
+        xs + ys
+      end.with_empty { Set[] }
+
       generator_for(Range) do |x|
         (x..x)
       end.with_shrink_function(&range_shrink).with_score_function do |f, r|

test/property_test.rb

@@ -243,6 +243,20 @@ def test_shrink_array
     end
   end
 
+  def test_shrink_set
+    gen = ::Minitest::Proptest::Gen.new(Random.new).for(Set, Int8)
+    property do
+      a = arbitrary Set, Int8
+      g = gen.force(a)
+      candidates = g.shrink_candidates
+
+      candidates.all? do |score, x|
+        score <= g.score &&
+          x.length <= a.length
+      end
+    end
+  end
+
   def test_shrink_range
     gen = ::Minitest::Proptest::Gen.new(Random.new).for(Range, Int8)
     property do