Add tests for MMTK_HEAP_MIN

Author: peterzhu2118

test/mmtk/test_configuration.rb

@@ -29,6 +29,11 @@ def test_MMTK_THREADS
     end
 
     def test_MMTK_HEAP_MIN
+      # Defaults to 1MiB
+      assert_separately([], <<~RUBY)
+        assert_equal(1 * 1024 * 1024, GC.config[:mmtk_heap_min])
+      RUBY
+
       # TODO: uncomment this test when the infinite loop is fixed
       # assert_separately([{ "MMTK_HEAP_MODE" => "dynamic", "MMTK_HEAP_MIN" => "1" }], <<~RUBY)
       #   assert_equal(1, GC.config[:mmtk_heap_min])
@@ -39,6 +44,12 @@ def test_MMTK_HEAP_MIN
       RUBY
     end
 
+    def test_MMTK_HEAP_MIN_is_ignored_for_fixed_heaps
+      assert_separately([{ "MMTK_HEAP_MODE" => "fixed", "MMTK_HEAP_MIN" => "1" }], <<~RUBY)
+        assert_nil(GC.config[:mmtk_heap_min])
+      RUBY
+    end
+
     def test_MMTK_HEAP_MAX
       assert_separately([{ "MMTK_HEAP_MODE" => "fixed", "MMTK_HEAP_MAX" => "100MiB" }], <<~RUBY)
         assert_equal(100 * 1024 * 1024, GC.config[:mmtk_heap_max])