Move constants under the TestCase

tool/lib/test/unit/assertions.rb

@@ -844,11 +844,6 @@ EOT
         result
       end
 
-      # kernel resolution can limit the minimum time we can measure
-      # [ruby-core:81540]
-      MIN_HZ = MiniTest::Unit::TestCase.windows? ? 67 : 100
-      MIN_MEASURABLE = 1.0 / MIN_HZ
-
       def assert_cpu_usage_low(msg = nil, pct: 0.05, wait: 1.0, stop: nil)
         require 'benchmark'
 

tool/lib/test/unit/testcase.rb

@@ -154,6 +154,11 @@ module Test
       PASSTHROUGH_EXCEPTIONS = [NoMemoryError, SignalException,
                                 Interrupt, SystemExit] # :nodoc:
 
+      # kernel resolution can limit the minimum time we can measure
+      # [ruby-core:81540]
+      MIN_HZ = windows? ? 67 : 100
+      MIN_MEASURABLE = 1.0 / MIN_HZ
+
       ##
       # Runs the tests reporting the status to +runner+