🔀 Merge pull request #464 from ruby/sequence_set/set_op_fuzz_tests

✅ Test `SequenceSet#xor` and fuzz test all set operations

Author: nevans

test/net/imap/test_sequence_set.rb

@@ -22,7 +22,7 @@ def compare_to_reference_set(nums, set, seqset)
     assert seqset.cover? sorted.sample 100
   end
 
-  test "compared to reference Set, add many random values" do
+  test "fuzz test: add numbers and compare to reference Set" do
     set    = Set.new
     seqset = SequenceSet.new
     10.times do
@@ -31,7 +31,7 @@ def compare_to_reference_set(nums, set, seqset)
     end
   end
 
-  test "compared to reference Set, add many large ranges" do
+  test "fuzz test: add ranges and compare to reference Set" do
     set    = Set.new
     seqset = SequenceSet.new
     (1..10_000).each_slice(250) do
@@ -40,6 +40,80 @@ def compare_to_reference_set(nums, set, seqset)
     end
   end
 
+  test "fuzz test: set union identities" do
+    10.times do
+      lhs = SequenceSet[Array.new(100) { rand(1..300) }]
+      rhs = SequenceSet[Array.new(100) { rand(1..300) }]
+      union = lhs | rhs
+      assert_equal union, rhs | lhs # commutative
+      assert_equal union, ~(~lhs & ~rhs) # De Morgan's Law
+      assert_equal union, lhs | (lhs ^ rhs)
+      assert_equal union, lhs | (rhs - lhs)
+      assert_equal union, (lhs & rhs) ^ (lhs ^ rhs)
+      mutable = lhs.dup
+      assert_equal union, mutable.merge(rhs)
+      assert_equal union, mutable
+    end
+  end
+
+  test "fuzz test: set intersection identities" do
+    10.times do
+      lhs = SequenceSet[Array.new(100) { rand(1..300) }]
+      rhs = SequenceSet[Array.new(100) { rand(1..300) }]
+      intersection = lhs & rhs
+      assert_equal intersection, rhs & lhs # commutative
+      assert_equal intersection, ~(~lhs | ~rhs) # De Morgan's Law
+      assert_equal intersection, lhs - ~rhs
+      assert_equal intersection, lhs - (lhs - rhs)
+      assert_equal intersection, lhs - (lhs ^ rhs)
+      assert_equal intersection, lhs ^ (lhs - rhs)
+    end
+  end
+
+  test "fuzz test: set subtraction identities" do
+    10.times do
+      lhs = SequenceSet[Array.new(100) { rand(1..300) }]
+      rhs = SequenceSet[Array.new(100) { rand(1..300) }]
+      difference = lhs - rhs
+      assert_equal difference, ~rhs - ~lhs
+      assert_equal difference, ~(~lhs | rhs)
+      assert_equal difference, lhs & (lhs ^ rhs)
+      assert_equal difference, lhs ^ (lhs & rhs)
+      assert_equal difference, rhs ^ (lhs | rhs)
+      mutable = lhs.dup
+      assert_equal difference, mutable.subtract(rhs)
+      assert_equal difference, mutable
+    end
+  end
+
+  test "fuzz test: set xor identities" do
+    10.times do
+      lhs = SequenceSet[Array.new(100) { rand(1..300) }]
+      rhs = SequenceSet[Array.new(100) { rand(1..300) }]
+      mid = SequenceSet[Array.new(100) { rand(1..300) }]
+      xor = lhs ^ rhs
+      assert_equal xor, rhs ^ lhs # commutative
+      assert_equal xor, (lhs | rhs) - (lhs & rhs)
+      assert_equal xor, (lhs ^ mid) ^ (mid ^ rhs)
+      assert_equal xor, ~lhs ^ ~rhs
+    end
+  end
+
+  test "fuzz test: set complement identities" do
+    10.times do
+      set = SequenceSet[Array.new(100) { rand(1..300) }]
+      complement = ~set
+      assert_equal set,        ~complement
+      assert_equal complement, ~set.dup
+      assert_equal complement, SequenceSet.full - set
+      mutable = set.dup
+      assert_equal complement, mutable.complement!
+      assert_equal complement, mutable
+      assert_equal set,        mutable.complement!
+      assert_equal set,        mutable
+    end
+  end
+
   test "#== equality by value (not by identity or representation)" do
     assert_equal SequenceSet.new, SequenceSet.new
     assert_equal SequenceSet.new("1"), SequenceSet[1]
@@ -612,6 +686,16 @@ def obj.to_sequence_set; 192_168.001_255 end
     assert_equal seqset["1,5,11:99"], seqset["1,5:6,8:9,11:99"].subtract("6:9")
   end
 
+  test "#xor" do
+    seqset = -> { SequenceSet.new(_1) }
+    assert_equal seqset["1:5,11:15"], seqset["1:10"] ^ seqset["6:15"]
+    assert_equal seqset["1,3,5:6"],   seqset[1..5]   ^ [2, 4, 6]
+    assert_equal SequenceSet.empty,   seqset[1..5]   ^ seqset[1..5]
+    assert_equal seqset["1:100"],     seqset["1:50"] ^ seqset["51:100"]
+    assert_equal seqset["1:50"],      seqset["1:50"] ^ SequenceSet.empty
+    assert_equal seqset["1:50"],      SequenceSet.empty ^ seqset["1:50"]
+  end
+
   test "#min" do
     assert_equal   3, SequenceSet.new("34:3").min
     assert_equal 345, SequenceSet.new("345,678").min