2 files changed, 40 insertions, 31 deletions
diff --git a/activesupport/test/json/decoding_test.rb b/activesupport/test/json/decoding_test.rb
index 07d7e530ca..80bf255080 100644
--- a/activesupport/test/json/decoding_test.rb
+++ b/activesupport/test/json/decoding_test.rb
@@ -73,22 +73,20 @@ class TestJSONDecoding < ActiveSupport::TestCase
 
   TESTS.each_with_index do |(json, expected), index|
     test "json decodes #{index}" do
-      prev = ActiveSupport.parse_json_times
-      ActiveSupport.parse_json_times = true
-      silence_warnings do
-        assert_equal expected, ActiveSupport::JSON.decode(json), "JSON decoding \
-        failed for #{json}"
+      with_parse_json_times(true) do
+        silence_warnings do
+          assert_equal expected, ActiveSupport::JSON.decode(json), "JSON decoding \
+          failed for #{json}"
+        end
       end
-      ActiveSupport.parse_json_times = prev
     end
   end
 
   test "json decodes time json with time parsing disabled" do
-    prev = ActiveSupport.parse_json_times
-    ActiveSupport.parse_json_times = false
-    expected = {"a" => "2007-01-01 01:12:34 Z"}
-    assert_equal expected, ActiveSupport::JSON.decode(%({"a": "2007-01-01 01:12:34 Z"}))
-    ActiveSupport.parse_json_times = prev
+    with_parse_json_times(false) do
+      expected = {"a" => "2007-01-01 01:12:34 Z"}
+      assert_equal expected, ActiveSupport::JSON.decode(%({"a": "2007-01-01 01:12:34 Z"}))
+    end
   end
 
   def test_failed_json_decoding
@@ -101,5 +99,15 @@ class TestJSONDecoding < ActiveSupport::TestCase
   def test_cannot_pass_unsupported_options
     assert_raise(ArgumentError) { ActiveSupport::JSON.decode("", create_additions: true) }
   end
+
+  private
+
+  def with_parse_json_times(value)
+    old_value = ActiveSupport.parse_json_times
+    ActiveSupport.parse_json_times = value
+    yield
+  ensure
+    ActiveSupport.parse_json_times = old_value
+  end
 end
 
diff --git a/activesupport/test/json/encoding_test.rb b/activesupport/test/json/encoding_test.rb
index f22d7b8b02..ad358ad21d 100644
--- a/activesupport/test/json/encoding_test.rb
+++ b/activesupport/test/json/encoding_test.rb
@@ -4,8 +4,11 @@ require 'abstract_unit'
 require 'active_support/core_ext/string/inflections'
 require 'active_support/json'
 require 'active_support/time'
+require 'time_zone_test_helpers'
 
 class TestJSONEncoding < ActiveSupport::TestCase
+  include TimeZoneTestHelpers
+
   class Foo
     def initialize(a, b)
       @a, @b = a, b
@@ -491,31 +494,28 @@ EXPECTED
 
   def test_twz_to_json_with_custom_time_precision
     with_standard_json_time_format(true) do
-      ActiveSupport::JSON::Encoding.time_precision = 0
-      zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
-      time = ActiveSupport::TimeWithZone.new(Time.utc(2000), zone)
-      assert_equal "\"1999-12-31T19:00:00-05:00\"", ActiveSupport::JSON.encode(time)
+      with_time_precision(0) do
+        zone = ActiveSupport::TimeZone['Eastern Time (US & Canada)']
+        time = ActiveSupport::TimeWithZone.new(Time.utc(2000), zone)
+        assert_equal "\"1999-12-31T19:00:00-05:00\"", ActiveSupport::JSON.encode(time)
+      end
     end
-  ensure
-    ActiveSupport::JSON::Encoding.time_precision = 3
   end
 
   def test_time_to_json_with_custom_time_precision
     with_standard_json_time_format(true) do
-      ActiveSupport::JSON::Encoding.time_precision = 0
-      assert_equal "\"2000-01-01T00:00:00Z\"", ActiveSupport::JSON.encode(Time.utc(2000))
+      with_time_precision(0) do
+        assert_equal "\"2000-01-01T00:00:00Z\"", ActiveSupport::JSON.encode(Time.utc(2000))
+      end
     end
-  ensure
-    ActiveSupport::JSON::Encoding.time_precision = 3
   end
 
   def test_datetime_to_json_with_custom_time_precision
     with_standard_json_time_format(true) do
-      ActiveSupport::JSON::Encoding.time_precision = 0
-      assert_equal "\"2000-01-01T00:00:00+00:00\"", ActiveSupport::JSON.encode(DateTime.new(2000))
+      with_time_precision(0) do
+        assert_equal "\"2000-01-01T00:00:00+00:00\"", ActiveSupport::JSON.encode(DateTime.new(2000))
+      end
     end
-  ensure
-    ActiveSupport::JSON::Encoding.time_precision = 3
   end
 
   def test_twz_to_json_when_wrapping_a_date_time
@@ -530,17 +530,18 @@ EXPECTED
       json_object[1..-2].scan(/([^{}:,\s]+):/).flatten.sort
     end
 
-    def with_env_tz(new_tz = 'US/Eastern')
-      old_tz, ENV['TZ'] = ENV['TZ'], new_tz
+    def with_standard_json_time_format(boolean = true)
+      old, ActiveSupport.use_standard_json_time_format = ActiveSupport.use_standard_json_time_format, boolean
       yield
     ensure
-      old_tz ? ENV['TZ'] = old_tz : ENV.delete('TZ')
+      ActiveSupport.use_standard_json_time_format = old
     end
 
-    def with_standard_json_time_format(boolean = true)
-      old, ActiveSupport.use_standard_json_time_format = ActiveSupport.use_standard_json_time_format, boolean
+    def with_time_precision(value)
+      old_value = ActiveSupport::JSON::Encoding.time_precision
+      ActiveSupport::JSON::Encoding.time_precision = value
       yield
     ensure
-      ActiveSupport.use_standard_json_time_format = old
+      ActiveSupport::JSON::Encoding.time_precision = old_value
     end
 end