Fix split_wast on asserts before the first module (#3206)

Normally a wast file has a module and then asserts on it, but
some tests have just asserts without a module. In that case,
set the module to None.

(This can happen if the asserts do not refer to a module,
and are at the top of the wast file.)

1 files changed, 6 insertions, 0 deletions

diff --git a/scripts/test/support.py b/scripts/test/support.py
index 8e4ef85e8..a4a61fc22 100644
--- a/scripts/test/support.py
+++ b/scripts/test/support.py
@@ -146,6 +146,12 @@ def split_wast(wastFile):
         elif chunk.startswith('(assert_invalid'):
             continue
         elif chunk.startswith(('(assert', '(invoke')):
+            # ret may be empty if there are some asserts before the first
+            # module. in that case these are asserts *without* a module, which
+            # are valid (they may check something that doesn't refer to a module
+            # in any way).
+            if not ret:
+                ret += [(None, [])]
             ret[-1][1].append(chunk)
     return ret