Fix timezone issue for logger period's tests

This is a retry of 181b966e75.
"Revert "Add a missing tests for Logger::Period module"" is also
reverted.

test/logger/test_logperiod.rb

@@ -0,0 +1,85 @@
+# coding: US-ASCII
+# frozen_string_literal: false
+require 'test/unit'
+require 'logger'
+require 'time'
+
+class TestLogPeriod < Test::Unit::TestCase
+  def test_next_rotate_time
+    time = Time.parse("2019-07-18 13:52:02")
+
+    daily_result = Logger::Period.next_rotate_time(time, 'daily')
+    next_day = Time.parse("2019-07-19 00:00:00")
+    assert_equal(next_day, daily_result)
+
+    weekly_result = Logger::Period.next_rotate_time(time, 'weekly')
+    next_week = Time.parse("2019-07-21 00:00:00")
+    assert_equal(next_week, weekly_result)
+
+    monthly_result = Logger::Period.next_rotate_time(time, 'monthly')
+    next_month = Time.parse("2019-08-1 00:00:00")
+    assert_equal(next_month, monthly_result)
+
+    result = Logger::Period.next_rotate_time(time, 'invalid')
+    assert_equal(time, result)
+  end
+
+  def test_next_rotate_time_extreme_cases
+    # First day of Month and Saturday
+    time = Time.parse("2018-07-01 00:00:00")
+
+    daily_result = Logger::Period.next_rotate_time(time, 'daily')
+    next_day = Time.parse("2018-07-02 00:00:00")
+    assert_equal(next_day, daily_result)
+
+    weekly_result = Logger::Period.next_rotate_time(time, 'weekly')
+    next_week = Time.parse("2018-07-08 00:00:00")
+    assert_equal(next_week, weekly_result)
+
+    monthly_result = Logger::Period.next_rotate_time(time, 'monthly')
+    next_month = Time.parse("2018-08-1 00:00:00")
+    assert_equal(next_month, monthly_result)
+
+    result = Logger::Period.next_rotate_time(time, 'invalid')
+    assert_equal(time, result)
+  end
+
+  def test_previous_period_end
+    time = Time.parse("2019-07-18 13:52:02")
+
+    daily_result = Logger::Period.previous_period_end(time, 'daily')
+    day_ago = Time.parse("2019-07-17 23:59:59")
+    assert_equal(day_ago, daily_result)
+
+    weekly_result = Logger::Period.previous_period_end(time, 'weekly')
+    week_ago = Time.parse("2019-07-13 23:59:59")
+    assert_equal(week_ago, weekly_result)
+
+    monthly_result = Logger::Period.previous_period_end(time, 'monthly')
+    month_ago = Time.parse("2019-06-30 23:59:59")
+    assert_equal(month_ago, monthly_result)
+
+    result = Logger::Period.previous_period_end(time, 'invalid')
+    assert_equal(time, result)
+  end
+
+  def test_previous_period_end_extreme_cases
+    # First day of Month and Saturday
+    time = Time.parse("2018-07-01 00:00:00")
+
+    daily_result = Logger::Period.previous_period_end(time, 'daily')
+    day_ago = Time.parse("2018-06-30 23:59:59")
+    assert_equal(day_ago, daily_result)
+
+    weekly_result = Logger::Period.previous_period_end(time, 'weekly')
+    week_ago = Time.parse("2018-06-30 23:59:59")
+    assert_equal(week_ago, weekly_result)
+
+    monthly_result = Logger::Period.previous_period_end(time, 'monthly')
+    month_ago = Time.parse("2018-06-30 23:59:59")
+    assert_equal(month_ago, monthly_result)
+
+    result = Logger::Period.previous_period_end(time, 'invalid')
+    assert_equal(time, result)
+  end
+end