1 files changed, 37 insertions, 0 deletions
diff --git a/spec/bundler/support/artifice/compact_index_partial_update.rb b/spec/bundler/support/artifice/compact_index_partial_update.rb
new file mode 100644
index 0000000000..bf6feab877
--- /dev/null
+++ b/spec/bundler/support/artifice/compact_index_partial_update.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+require File.expand_path("../compact_index", __FILE__)
+
+Artifice.deactivate
+
+class CompactIndexPartialUpdate < CompactIndexAPI
+  # Stub the server to never return 304s. This simulates the behaviour of
+  # Fastly / Rubygems ignoring ETag headers.
+  def not_modified?(_checksum)
+    false
+  end
+
+  get "/versions" do
+    cached_versions_path = File.join(
+      Bundler.rubygems.user_home, ".bundle", "cache", "compact_index",
+      "localgemserver.test.80.dd34752a738ee965a2a4298dc16db6c5", "versions"
+    )
+
+    # Verify a cached copy of the versions file exists
+    unless File.read(cached_versions_path).start_with?("created_at: ")
+      raise("Cached versions file should be present and have content")
+    end
+
+    # Verify that a partial request is made, starting from the index of the
+    # final byte of the cached file.
+    unless env["HTTP_RANGE"] == "bytes=#{File.read(cached_versions_path).bytesize - 1}-"
+      raise("Range header should be present, and start from the index of the final byte of the cache.")
+    end
+
+    etag_response do
+      # Return the exact contents of the cache.
+      File.read(cached_versions_path)
+    end
+  end
+end
+
+Artifice.activate_with(CompactIndexPartialUpdate)