Test allocation counts

Author: jhawthorn

test/test_allocations.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class TestAllocations < Minitest::Test
+  def test_integer
+    assert_encode_allocations 1, [1, 2, 3, 4, 5]
+  end
+
+  def test_boolean
+    assert_encode_allocations 1, [true, false, true, false, true, false]
+  end
+
+  def test_float
+    # FIXME: ideally would not allocate
+    assert_encode_allocations 6, [1.0, 2.0, 3.0, 4.0, 5.0]
+  end
+
+  def test_symbol
+    assert_encode_allocations 1, %i[foo bar baz quux]
+  end
+
+  def test_string
+    assert_encode_allocations 1, %w[foo bar baz quux]
+  end
+
+  def test_array
+    assert_encode_allocations 1, [[], [], [], [], []]
+  end
+
+  def test_hash
+    assert_encode_allocations 1, {foo: 1, bar: 2, baz: 3, quux: 4}
+  end
+
+  def assert_encode_allocations(expected, data)
+    allocations = measure_allocations { RapidJSON.encode(data) }
+    assert_equal expected, allocations
+  end
+
+  def measure_allocations
+    i = 0
+    while i < 2
+      before = allocations
+      yield
+      after = allocations
+      i += 1
+    end
+    after - before
+  end
+
+  def allocations
+    GC.stat(:total_allocated_objects)
+  end
+end