Test suite run with concurrent workers

Part of #1

test/sample_suites/passing_concurrent/spec/a_spec.rb

@@ -0,0 +1,5 @@
+require_relative "shared"
+
+RSpec.describe do
+  it_behaves_like "kinda slow example"
+end

test/sample_suites/passing_concurrent/spec/b_spec.rb

@@ -0,0 +1,5 @@
+require_relative "shared"
+
+RSpec.describe do
+  it_behaves_like "kinda slow example"
+end

test/sample_suites/passing_concurrent/spec/c_spec.rb

@@ -0,0 +1,5 @@
+require_relative "shared"
+
+RSpec.describe do
+  it_behaves_like "kinda slow example"
+end

test/sample_suites/passing_concurrent/spec/d_spec.rb

@@ -0,0 +1,5 @@
+require_relative "shared"
+
+RSpec.describe do
+  it_behaves_like "kinda slow example"
+end

test/sample_suites/passing_concurrent/spec/e_spec.rb

@@ -0,0 +1,5 @@
+require_relative "shared"
+
+RSpec.describe do
+  it_behaves_like "kinda slow example"
+end

test/sample_suites/passing_concurrent/spec/shared.rb

@@ -0,0 +1,6 @@
+RSpec.shared_examples "kinda slow example" do
+  it do
+    sleep 2
+    expect(true).to be true
+  end
+end

test/test_concurrent_workers.rb

@@ -0,0 +1,32 @@
+require "test_helpers"
+
+class TestConcurrentWorkers < RSpecQTest
+  # The 'passing_concurrent' suite contains 5 spec files with a single example,
+  # taking 1". We spawn that many workers so we expect roughly 1 second total
+  # execution time. We add 1 second more to account for fork and rspec boot
+  # overhead
+  def test_passing_suite
+    build_id = rand_id
+    pids = []
+    job_count = 5
+
+    start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
+
+    job_count.times do
+      pids << start_worker(build_id: build_id, suite: "passing_concurrent")
+    end
+
+    pids.each { |p| Process.wait(p) }
+
+    elapsed = Process.clock_gettime(Process::CLOCK_MONOTONIC) - start
+
+    assert_operator elapsed, :<, 5
+
+    queue = RSpecQ::Queue.new(build_id, "foo", REDIS_HOST)
+
+    assert_queue_well_formed(queue)
+    assert queue.build_successful?
+    assert_equal job_count, queue.example_count
+    assert_equal job_count, queue.redis.zcard(queue.key_worker_heartbeats)
+  end
+end

test/test_helpers.rb

@@ -4,6 +4,7 @@
 
 module TestHelpers
   REDIS_HOST = "127.0.0.1".freeze
+  EXEC_CMD = "bundle exec rspecq"
 
   def rand_id
     SecureRandom.hex(4)
@@ -23,7 +24,7 @@ def exec_build(path, args="")
     build_id = rand_id
 
     Dir.chdir(suite_path(path)) do
-      out = `bundle exec rspecq --worker #{worker_id} --build #{build_id} #{args}`
+      out = `#{EXEC_CMD} --worker #{worker_id} --build #{build_id} #{args}`
       puts out if ENV["RSPECQ_DEBUG"]
     end
 
@@ -57,6 +58,14 @@ def assert_processed_jobs(exp, queue)
   def suite_path(path)
     File.join("test", "sample_suites", path)
   end
+
+  def start_worker(build_id:, worker_id: rand_id, suite:)
+    Process.spawn(
+      "#{EXEC_CMD} -w #{worker_id} -b #{build_id}",
+      chdir: suite_path(suite),
+      out: (ENV["RSPECQ_DEBUG"] ? :out : "/dev/null"),
+    )
+  end
 end
 
 # To be subclassed from all test cases.