Merge pull request #8496 from reitermarkus/debug-git

Properly fix Git error in tests.

Library/Homebrew/test/utils/git_spec.rb

@@ -3,9 +3,14 @@
 require "utils/git"
 
 describe Utils::Git do
-  before do
+  around do |example|
+    described_class.clear_available_cache
+    example.run
+  ensure
     described_class.clear_available_cache
+  end
 
+  before do
     git = HOMEBREW_SHIMS_PATH/"scm/git"
 
     HOMEBREW_CACHE.cd do
@@ -145,6 +150,8 @@
       end
 
       it "installs git" do
+        skip if ENV["HOMEBREW_TEST_GENERIC_OS"]
+
         expect(described_class).to receive(:available?).and_return(false)
         expect(described_class).to receive(:safe_system).with(HOMEBREW_BREW_FILE, "install", "git").and_return(true)
         expect(described_class).to receive(:available?).and_return(true)

Library/Homebrew/utils/git.rb

@@ -94,13 +94,12 @@ def ensure_installed!
         begin
           oh1 "Installing #{Formatter.identifier("git")}"
 
-          # We need to unset `HOMEBREW_TEST_GENERIC_OS`, otherwise `git` will be
-          # installed from source in tests that need it. This is slow and will
-          # also likely fail due to `OS::Linux` and `OS::Mac` being undefined.
-          with_env "HOMEBREW_TEST_GENERIC_OS" => nil do
-            safe_system HOMEBREW_BREW_FILE, "install", "git"
-            clear_available_cache
-          end
+          # Otherwise `git` will be installed from source in tests that need it. This is slow
+          # and will also likely fail due to `OS::Linux` and `OS::Mac` being undefined.
+          raise "Refusing to install Git on a generic OS." if ENV["HOMEBREW_TEST_GENERIC_OS"]
+
+          safe_system HOMEBREW_BREW_FILE, "install", "git"
+          clear_available_cache
         rescue
           raise "Git is unavailable"
         end