make pipeline test non-blocking for windows kernel happiness

test/spawn.jl

@@ -248,24 +248,29 @@ let bad = "bad\0name"
     @test_throws ArgumentError run(setenv(`echo hello`, "good"=>bad))
 end
 
-let out = Pipe(), echo = `$exename -f -e 'print(STDOUT, " 1\t", readall(STDIN))'`
+let out = Pipe(), echo = `$exename -f -e 'print(STDOUT, " 1\t", readall(STDIN))'`, ready = Condition()
     @test_throws ArgumentError write(out, "not open error")
-    open(echo, "w", out) do in1
-        open(echo, "w", out) do in2
-            write(in1, 'h')
-            write(in2, UInt8['w'])
-            println(in1, "ello")
-            write(in2, "orld\n")
+    @async begin # spawn writer task
+        open(echo, "w", out) do in1
+            open(echo, "w", out) do in2
+                notify(ready)
+                write(in1, 'h')
+                write(in2, UInt8['w'])
+                println(in1, "ello")
+                write(in2, "orld\n")
+            end
         end
+        show(out, out)
+        notify(ready)
+        @test isreadable(out)
+        @test iswritable(out)
+        close(out.in)
+        @test_throws ArgumentError write(out, "now closed error")
+        @test isreadable(out)
+        @test !iswritable(out)
+        @test isopen(out)
     end
-    show(out, out)
-    @test isreadable(out)
-    @test iswritable(out)
-    close(out.in)
-    @test_throws ArgumentError write(out, "now closed error")
-    @test isreadable(out)
-    @test !iswritable(out)
-    @test isopen(out)
+    wait(ready) # wait for writer task to be ready before using `out`
     @test nb_available(out) == 0
     @test endswith(readuntil(out, '1'), '1')
     @test read(out, UInt8) == '\t'
@@ -285,7 +290,7 @@ let out = Pipe(), echo = `$exename -f -e 'print(STDOUT, " 1\t", readall(STDIN))'
     @test ln1 == "orld\n"
     @test isempty(readbytes(out))
     @test eof(out)
-    @test desc == "Pipe(open => open, 0 bytes waiting)"
+    @test desc == "Pipe(open => active, 0 bytes waiting)"
 end
 
 # issue #8529