Fix: new_thread spec helper now returns a thread or isolated context

We can't join on a thread because it may not terminate anymore. We must
call the `#wait` method of the isolated context to know when the
isolated fiber has terminated. The method is conveniently aliased as
`#join` so we don't need to handle the type in most cases.

Author: ysbaddaden

spec/std/fiber/execution_context/global_queue_spec.cr

@@ -100,7 +100,7 @@ describe Fiber::ExecutionContext::GlobalQueue do
       queue = Fiber::ExecutionContext::GlobalQueue.new(Thread::Mutex.new)
       ready = Thread::WaitGroup.new(n)
 
-      threads = Array(Thread).new(n) do |i|
+      threads = n.times.map do |i|
         new_thread("ONE-#{i}") do
           slept = 0
           ready.done
@@ -118,7 +118,7 @@ describe Fiber::ExecutionContext::GlobalQueue do
             end
           end
         end
-      end
+      end.to_a
       ready.wait
 
       fibers.each_with_index do |fc, i|
@@ -143,7 +143,7 @@ describe Fiber::ExecutionContext::GlobalQueue do
       queue = Fiber::ExecutionContext::GlobalQueue.new(Thread::Mutex.new)
       ready = Thread::WaitGroup.new(n)
 
-      threads = Array(Thread).new(n) do |i|
+      threads = n.times.map do |i|
         new_thread("BULK-#{i}") do
           slept = 0
 
@@ -196,7 +196,7 @@ describe Fiber::ExecutionContext::GlobalQueue do
             Thread.sleep(1.nanosecond) # don't burn CPU
           end
         end
-      end
+      end.to_a
       ready.wait
 
       # enqueue in batches of 5

spec/std/fiber/execution_context/runnables_spec.cr

@@ -196,7 +196,7 @@ describe Fiber::ExecutionContext::Runnables do
         Fiber::ExecutionContext::Runnables(16).new(global_queue)
       end
 
-      threads = Array(Thread).new(n) do |i|
+      threads = n.times.map do |i|
         new_thread("RUN-#{i}") do
           runnables = all_runnables[i]
           slept = 0
@@ -240,7 +240,7 @@ describe Fiber::ExecutionContext::Runnables do
             Thread.sleep(1.nanosecond) # don't burn CPU
           end
         end
-      end
+      end.to_a
       ready.wait
 
       # enqueue in batches

spec/std/thread_spec.cr

@@ -21,7 +21,11 @@ pending_interpreted describe: Thread do
     current = nil
     thread = new_thread { current = Thread.current }
     thread.join
-    current.should be(thread)
+    {% if flag?(:execution_context) %}
+      current.should be(thread.@thread)
+    {% else %}
+      current.should be(thread)
+    {% end %}
     current.should_not be(Thread.current)
   ensure
     # avoids a "GC Warning: Finalization cycle" caused by *current*

spec/support/thread.cr

@@ -1,8 +1,7 @@
 {% begin %}
-  def new_thread(name = nil, &block) : Thread
+  def new_thread(name = nil, &block)
     {% if flag?(:execution_context) %}
-      ctx = Fiber::ExecutionContext::Isolated.new(name: name || "SPEC") { block.call }
-      ctx.@thread
+      Fiber::ExecutionContext::Isolated.new(name: name || "SPEC") { block.call }
     {% else %}
       Thread.new(name) { block.call }
     {% end %}