From 839b7d44cc014176f0bed4bc232f048125358436 Mon Sep 17 00:00:00 2001
From: Carlo Cabrera <30379873+carlocab@users.noreply.github.com>
Date: Tue, 4 Apr 2023 02:28:56 +0800
Subject: [PATCH] determine-test-runners: test failure modes

---
 .../test/dev-cmd/determine-test-runners_spec.rb  | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Library/Homebrew/test/dev-cmd/determine-test-runners_spec.rb b/Library/Homebrew/test/dev-cmd/determine-test-runners_spec.rb
index c3bddc98cb..520035f741 100644
--- a/Library/Homebrew/test/dev-cmd/determine-test-runners_spec.rb
+++ b/Library/Homebrew/test/dev-cmd/determine-test-runners_spec.rb
@@ -35,6 +35,22 @@ describe "brew determine-test-runners" do
       .and be_a_failure
   end
 
+  it "fails when the necessary environment variables are missing", :integration_test, :needs_linux do
+    setup_test_formula "testball"
+
+    runner_env.each_key do |k|
+      next if ["GITHUB_RUN_ID", "GITHUB_RUN_ATTEMPT"].include? k
+
+      runner_env_dup = runner_env.dup
+      runner_env_dup.delete(k)
+
+      expect { brew "determine-test-runners", "testball", runner_env_dup }
+        .to not_to_output.to_stdout
+        .and output("Error: #{k} is not defined\n").to_stderr
+        .and be_a_failure
+    end
+  end
+
   it "assigns all runners for formulae without any requirements", :integration_test, :needs_linux do
     setup_test_formula "testball"