diff --git a/test/models/time_series/trend_test.rb b/test/models/time_series/trend_test.rb
index fe2027e0..8f532aaa 100644
--- a/test/models/time_series/trend_test.rb
+++ b/test/models/time_series/trend_test.rb
@@ -9,28 +9,38 @@ class TimeSeries::TrendTest < ActiveSupport::TestCase
   end
 
   test "up" do
-    assert_equal "up", TimeSeries::Trend.new(current: 100, previous: 50).direction
+    trend = TimeSeries::Trend.new(current: 100, previous: 50)
+    assert_equal "up", trend.direction
   end
 
   test "down" do
-    assert_equal "down", TimeSeries::Trend.new(current: 50, previous: 100).direction
+    trend = TimeSeries::Trend.new(current: 50, previous: 100)
+    assert_equal "down", trend.direction
   end
 
   test "flat" do
-    assert_equal "flat", TimeSeries::Trend.new(current: 100, previous: 100).direction
-    assert_equal "flat", TimeSeries::Trend.new(current: 100, previous: nil).direction
+    trend1 = TimeSeries::Trend.new(current: 100, previous: 100)
+    trend3 = TimeSeries::Trend.new(current: 100, previous: nil)
+    trend2 = TimeSeries::Trend.new(current: nil, previous: nil)
+    assert_equal "flat", trend1.direction
+    assert_equal "flat", trend2.direction
+    assert_equal "flat", trend3.direction
   end
 
   test "infinitely up" do
-    assert_equal "up", TimeSeries::Trend.new(current: 100, previous: 0).direction
+    trend = TimeSeries::Trend.new(current: 100, previous: 0)
+    assert_equal "up", trend.direction
   end
 
   test "infinitely down" do
-    assert_equal "down", TimeSeries::Trend.new(current: nil, previous: 100).direction
-    assert_equal "down", TimeSeries::Trend.new(current: 0, previous: 100).direction
+    trend1 = TimeSeries::Trend.new(current: nil, previous: 100)
+    trend2 = TimeSeries::Trend.new(current: 0, previous: 100)
+    assert_equal "down", trend1.direction
+    assert_equal "down", trend2.direction
   end
 
   test "empty" do
-    assert_equal "flat", TimeSeries::Trend.new(current: nil, previous: nil).direction
+    trend = TimeSeries::Trend.new(current: nil, previous: nil)
+    assert_equal "flat", trend.direction
   end
 end