Prevent invalid encoding for files blowing up Source.from_file

.github/workflows/ci.yml

@@ -133,7 +133,12 @@ jobs:
       JRUBY_OPTS: ${{ matrix.container.jruby_opts || '--dev' }}
       NO_COVERAGE: true
     steps:
-      - uses: actions/checkout@v3
+      - run: git config --global --add safe.directory $GITHUB_WORKSPACE
+      - run: git init $GITHUB_WORKSPACE
+      - run: git remote add origin https://github.com/rspec/rspec-support
+      - run: git config --local gc.auto 0
+      - run: git fetch --no-tags --prune --no-recurse-submodules --depth=1 origin +$GITHUB_SHA:$GITHUB_REF
+      - run: git checkout --progress --force $GITHUB_REF
       - run: ${{ matrix.container.pre }}
       - run: script/legacy_setup.sh
       - run: ${{ matrix.container.post }}

lib/rspec/support/source.rb

@@ -14,14 +14,22 @@ class Source
       # stubbed out within tests.
       class File
         class << self
-          [:read, :expand_path].each do |method_name|
-            define_method(method_name, &::File.method(method_name))
+          define_method(:expand_path, &::File.method(:expand_path))
+
+          if RUBY_VERSION.to_f > 1.9
+            define_method(:binread, &::File.method(:binread))
+          else
+            define_method(:binread, &::File.method(:read))
           end
         end
       end
 
       def self.from_file(path)
-        source = File.read(path)
+        # We must use `binread` here, there is no spec for this behaviour
+        # as its proven troublesome to replicate within our spec suite, but
+        # to manually verify run:
+        # `bundle exec rspec spec/support/source_broken_example`
+        source = File.binread(path)
         new(source, path)
       end
 

spec/support/source_broken_example

@@ -0,0 +1,8 @@
+Encoding.default_internal = Encoding::BINARY
+
+describe UndeclaredModule do
+  # the missing constant can be anything
+  it 'crashes and does not even parse this' do
+    'привет'
+  end
+end