Refactored version of execProcesses with test.

tests/osproc/texecps.nim

@@ -0,0 +1,32 @@
+discard """
+  file: "texecps.nim"
+  output: ""
+"""
+
+import osproc, streams, strutils, os
+
+const NumberOfProcesses = 13
+
+var gResults {.threadvar.}: seq[string]
+
+proc execCb(idx: int, p: Process) =
+  let exitCode = p.peekExitCode
+  if exitCode < len(gResults):
+    gResults[exitCode] = p.outputStream.readAll.strip
+
+when isMainModule:
+
+  if paramCount() == 0:
+    gResults = newSeq[string](NumberOfProcesses)
+    var checks = newSeq[string](NumberOfProcesses)
+    var commands = newSeq[string](NumberOfProcesses)
+    for i in 0..len(commands) - 1:
+      commands[i] = getAppFileName() & " " & $i
+      checks[i] = $i
+    let cres = execProcesses(commands, options = {poStdErrToStdOut},
+                             afterRunEvent = execCb)
+    doAssert(cres == len(commands) - 1)
+    doAssert(gResults == checks)
+  else:
+    echo paramStr(1)
+    programResult = parseInt(paramStr(1))