Show better explanation what to do when there is missing test suite token environment variable

CHANGELOG.md

@@ -8,6 +8,10 @@
 
     https://github.com/KnapsackPro/knapsack_pro-ruby/pull/34
 
+* Show better explanation what to do when there is missing test suite token environment variable.
+
+    https://github.com/KnapsackPro/knapsack_pro-ruby/pull/35
+
 https://github.com/KnapsackPro/knapsack_pro-ruby/compare/v0.36.0...v0.37.0
 
 ### 0.36.0

lib/knapsack_pro/config/env.rb

@@ -120,7 +120,8 @@ def fixed_queue_split
         end
 
         def test_suite_token
-          required_env('KNAPSACK_PRO_TEST_SUITE_TOKEN')
+          env_name = 'KNAPSACK_PRO_TEST_SUITE_TOKEN'
+          ENV[env_name] || raise("Missing environment variable #{env_name}. You should set environment variable like #{env_name}_RSPEC (note there is suffix _RSPEC at the end). knapsack_pro gem will set #{env_name} based on #{env_name}_RSPEC value. If you use other test runner than RSpec then use proper suffix.")
         end
 
         def test_suite_token_rspec

spec/knapsack_pro/config/env_spec.rb

@@ -466,7 +466,7 @@
 
     context "when ENV doesn't exist" do
       it do
-        expect { subject }.to raise_error('Missing environment variable KNAPSACK_PRO_TEST_SUITE_TOKEN')
+        expect { subject }.to raise_error('Missing environment variable KNAPSACK_PRO_TEST_SUITE_TOKEN. You should set environment variable like KNAPSACK_PRO_TEST_SUITE_TOKEN_RSPEC (note there is suffix _RSPEC at the end). knapsack_pro gem will set KNAPSACK_PRO_TEST_SUITE_TOKEN based on KNAPSACK_PRO_TEST_SUITE_TOKEN_RSPEC value. If you use other test runner than RSpec then use proper suffix.')
       end
     end
   end