Added test for missing columns with cohort analysis [skip ci]

Author: ankane

test/cohort_analysis_test.rb

@@ -11,6 +11,11 @@ def test_cohort_time
     assert_match "1 cohort", response.body
   end
 
+  def test_missing_columns
+    run_query "SELECT 1 /* cohort analysis */", query_id: 1
+    assert_match "alert-danger", response.body
+  end
+
   def test_cohort_period_default
     query = create_query(statement: "SELECT 1 AS user_id, NOW() AS conversion_time /* cohort analysis */")
     get blazer.query_path(query)