tests/import: Add test for importing invalid .mpy file.

tests/import/mpy_invalid.py

@@ -0,0 +1,67 @@
+# test importing of invalid .mpy files
+
+import sys, uio
+
+try:
+    uio.IOBase
+    import uos
+    uos.mount
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
+
+
+class UserFile(uio.IOBase):
+    def __init__(self, data):
+        self.data = data
+        self.pos = 0
+    def read(self):
+        return self.data
+    def readinto(self, buf):
+        n = 0
+        while n < len(buf) and self.pos < len(self.data):
+            buf[n] = self.data[self.pos]
+            n += 1
+            self.pos += 1
+        return n
+    def ioctl(self, req, arg):
+        return 0
+
+
+class UserFS:
+    def __init__(self, files):
+        self.files = files
+    def mount(self, readonly, mksfs):
+        pass
+    def umount(self):
+        pass
+    def stat(self, path):
+        if path in self.files:
+            return (32768, 0, 0, 0, 0, 0, 0, 0, 0, 0)
+        raise OSError
+    def open(self, path, mode):
+        return UserFile(self.files[path])
+
+
+# these are the test .mpy files
+user_files = {
+    '/mod0.mpy': b'', # empty file
+    '/mod1.mpy': b'M', # too short header
+    '/mod2.mpy': b'M\x00\x00\x00', # bad version
+}
+
+# create and mount a user filesystem
+uos.mount(UserFS(user_files), '/userfs')
+sys.path.append('/userfs')
+
+# import .mpy files from the user filesystem
+for i in range(len(user_files)):
+    mod = 'mod%u' % i
+    try:
+        __import__(mod)
+    except ValueError as er:
+        print(mod, 'ValueError', er)
+
+# unmount and undo path addition
+uos.umount('/userfs')
+sys.path.pop()

tests/import/mpy_invalid.py.exp

@@ -0,0 +1,3 @@
+mod0 ValueError incompatible .mpy file
+mod1 ValueError incompatible .mpy file
+mod2 ValueError incompatible .mpy file