Add support for set difference

lib/kredis/types/set.rb

@@ -1,5 +1,8 @@
 class Kredis::Types::Set < Kredis::Types::Proxying
-  proxying :smembers, :sadd, :srem, :multi, :del, :sismember, :scard, :spop
+  proxying :smembers, :sadd, :srem, :multi, :del, :sismember, :scard, :spop,
+           :sdiff, :sdiffstore,
+           :sunion, :sunionstore,
+           :sinter, :sinterstore
 
   attr_accessor :typed
 
@@ -39,4 +42,40 @@ def take
   def clear
     del
   end
+
+  def -(value)
+    diff value
+  end
+
+  def diff(value, store: nil)
+    if store
+      store.sdiffstore key, value.key
+    else
+      sdiff value.key
+    end
+  end
+
+  def &(value)
+    intersection value
+  end
+
+  def intersection(value, store: nil)
+    if store
+      store.sinterstore key, value.key
+    else
+      sinter value.key
+    end
+  end
+
+  def +(value)
+    union value
+  end
+
+  def union(value, store: nil)
+    if store
+      store.sunionstore key, value.key
+    else
+      sunion value.key
+    end
+  end
 end

test/types/set_test.rb

@@ -63,6 +63,60 @@ class SetTest < ActiveSupport::TestCase
     assert_equal [], @set.members
   end
 
+  test "-" do
+    @set.add %w[1 2 3 4 5]
+    subset = Kredis.set "otherset"
+    subset.add %w[2 3 4]
+    assert_equal (@set - subset), %w[1 5]
+  end
+
+  test "diff" do
+    @set.add %w[1 2 3 4 5]
+    subset = Kredis.set "otherset"
+    subset.add %w[2 3 4]
+    assert_equal (@set.diff(subset)), %w[1 5]
+
+    result = Kredis.set "resultset"
+    @set.diff(subset, store: result)
+    assert_equal result.members, %w[1 5]
+  end
+
+  test "+" do
+    @set.add %w[1 2 3 4 5]
+    otherset = Kredis.set "otherset"
+    otherset.add %w[5 6 7 8 9]
+    assert_equal (@set + otherset), %w[1 2 3 4 5 6 7 8 9]
+  end
+
+  test "union" do
+    @set.add %w[1 2 3 4 5]
+    otherset = Kredis.set "otherset"
+    otherset.add %w[5 6 7 8 9]
+    assert_equal (@set.union(otherset)), %w[1 2 3 4 5 6 7 8 9]
+
+    result = Kredis.set "resultset"
+    @set.union(otherset, store: result)
+    assert_equal result.members, %w[1 2 3 4 5 6 7 8 9]
+  end
+
+  test "&" do
+    @set.add %w[1 2 3 4 5]
+    otherset = Kredis.set "otherset"
+    otherset.add %w[4 5 6 7]
+    assert_equal (@set & otherset), %w[4 5]
+  end
+
+  test "intersection" do
+    @set.add %w[1 2 3 4 5]
+    otherset = Kredis.set "otherset"
+    otherset.add %w[4 5 6 7]
+    assert_equal (@set.intersection(otherset)), %w[4 5]
+
+    result = Kredis.set "resultset"
+    @set.intersection(otherset, store: result)
+    assert_equal result.members, %w[4 5]
+  end
+
   test "typed as floats" do
     @set = Kredis.set "mylist", typed: :float