Another strategy

script/test-redirections

@@ -3,15 +3,16 @@
 require 'socket'
 
 # Start a webserver on a given port, serving a 301 redirection to a specific location
-def start_server(port, location)
+def start_server(port, location, log_mode)
   server = TCPServer.new(port)
   puts "Server started on port #{port}"
 
   loop do
+    # Block until a client connects
     client = server.accept
 
     # Append a hit in the file
-    File.open("/tmp/bad-redirection#{ENV["RUBY_VERSION"]}.log", 'a') do |file|
+    File.open("/tmp/bad-redirection#{ENV["RUBY_VERSION"]}.log", log_mode) do |file|
       file.sync = true # no bufferring
       file.print("HIT #{port} ")
     end
@@ -38,7 +39,7 @@ end
 
 # Go!
 threads = []
-threads << Thread.new { start_server(9988, 'http://127.0.0.1:9987') } # HTTP 301
-threads << Thread.new { start_server(9987, 'ftp://127.0.0.1:9986') }  # HTTP 301
-threads << Thread.new { start_server(9986, 'STOP') }                  # TCP close
+threads << Thread.new { start_server(9988, 'http://127.0.0.1:9987', "w") } # HTTP 301
+threads << Thread.new { start_server(9987, 'ftp://127.0.0.1:9986', "a") }  # HTTP 301
+threads << Thread.new { start_server(9986, 'STOP', "a") }                  # TCP close
 threads.each(&:join)

spec/github_pages_health_check/domain_spec.rb

@@ -673,13 +673,6 @@
 
   context "Protocol redirections" do
     let(:log_file) { "/tmp/bad-redirection#{ENV["RUBY_VERSION"]}.log" }
-    before do
-      File.open(log_file, "w") do |file|
-        # Just truncate the file (without buffering to avoid flakiness)
-        file.sync = true
-      end
-      sleep(0.5) # slow down just a little to limit flakiness too
-    end
 
     it "it follows ftp if requested" do
       # Make a real request to a local server started with /script/test-redirections
@@ -689,6 +682,7 @@
       )
 
       # Confirm port 9986 was hit (it is the FTP one)
+      sleep(0.1) until File.exist?(log_file)
       expect(File.read(log_file).strip).to eq("HIT 9988 HIT 9987 HIT 9986")
     end
 
@@ -700,6 +694,7 @@
       )
 
       # Confirm port 9986 was NOT hit (it is the FTP one)
+      sleep(0.1) until File.exist?(log_file)
       expect(File.read(log_file).strip).to eq("HIT 9988 HIT 9987")
     end
   end