From 328b63a5b4a83070b5381ed6a9de4d454ea65e9e Mon Sep 17 00:00:00 2001
From: Philip Harrison <philip@mailharrison.com>
Date: Wed, 16 Jun 2021 10:12:35 +0100
Subject: [PATCH] Raise on ruby 2.7 deprecation warnings

Break tests if we introduce any ruby 2.7 deprecation warnings.
---
 .github/workflows/ci.yml            |  1 +
 common/spec/spec_helper.rb          |  1 +
 common/spec/warning_monkey_patch.rb | 23 +++++++++++++++++++++++
 3 files changed, 25 insertions(+)
 create mode 100644 common/spec/warning_monkey_patch.rb

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 842c71452e..0088078d0f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -88,6 +88,7 @@ jobs:
         run: |
           docker run \
             --env "CI=true" \
+            --env "RAISE_ON_WARNINGS=true" \
             --env "DEPENDABOT_TEST_ACCESS_TOKEN=${{ secrets.GITHUB_TOKEN }}" \
             --env "SUITE_NAME=${{ matrix.suite.name }}" \
             --rm "$CORE_CI_IMAGE" bash -c \
diff --git a/common/spec/spec_helper.rb b/common/spec/spec_helper.rb
index b0bfa57f4f..b3184786d6 100644
--- a/common/spec/spec_helper.rb
+++ b/common/spec/spec_helper.rb
@@ -10,6 +10,7 @@
 
 require "dependabot/dependency_file"
 require_relative "dummy_package_manager/dummy"
+require_relative "warning_monkey_patch"
 
 if ENV["COVERAGE"]
   SimpleCov::Formatter::Console.output_style = "block"
diff --git a/common/spec/warning_monkey_patch.rb b/common/spec/warning_monkey_patch.rb
new file mode 100644
index 0000000000..c7699f25a6
--- /dev/null
+++ b/common/spec/warning_monkey_patch.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+ALLOW_PATTERNS = [
+  # Ignore parser warnings for ruby 2.7 minor version mismatches
+  # TODO: Fix these by upgrading to ruby 2.7.3 (requires ubuntu upgrade)
+  %r{parser/current is loading parser/ruby27},
+  /2.7.\d-compliant syntax, but you are running 2.7.\d/,
+  %r{whitequark/parser}
+].freeze
+
+# Called internally by Ruby for all warnings
+module Warning
+  def self.warn(message)
+    $stderr.print(message)
+
+    raise message if ENV["RAISE_ON_WARNINGS"].to_s == "true" && ALLOW_PATTERNS.none? { |pattern| pattern =~ message }
+
+    return unless ENV["DEBUG_WARNINGS"]
+
+    warn caller
+    $stderr.puts
+  end
+end