Multiple exception idents in except for async. Ref #1487.

tests/async/tasyncfile.nim

@@ -1,5 +1,5 @@
 discard """
-  file: "tasyncexceptions.nim"
+  file: "tasyncfile.nim"
   exitcode: 0
 """
 import asyncfile, asyncdispatch, os

tests/async/tasynctry.nim

@@ -0,0 +1,51 @@
+discard """
+  file: "tasynctry.nim"
+  exitcode: 0
+  output: '''
+Generic except
+Specific except
+Multiple idents in except
+Multiple except branches
+Multiple except branches 2
+'''
+"""
+import asyncdispatch
+
+# Here we are testing the ability to catch exceptions.
+
+proc foobar() {.async.} =
+  if 5 == 5:
+    raise newException(EInvalidIndex, "Test")
+
+proc catch() {.async.} =
+  # TODO: Create a test for when exceptions are not caught.
+  try:
+    await foobar()
+  except:
+    echo("Generic except")
+
+  try:
+    await foobar()
+  except EInvalidIndex:
+    echo("Specific except")
+
+  try:
+    await foobar()
+  except OSError, EInvalidField, EInvalidIndex:
+    echo("Multiple idents in except")
+
+  try:
+    await foobar()
+  except OSError, EInvalidField:
+    assert false
+  except EInvalidIndex:
+    echo("Multiple except branches")
+
+  try:
+    await foobar()
+  except EInvalidIndex:
+    echo("Multiple except branches 2")
+  except OSError, EInvalidField:
+    assert false
+
+asyncCheck catch()