tests: Add new subdir "stress/" specifically for stress tests.

tests/run-tests

@@ -365,7 +365,7 @@ def main():
         if args.test_dirs is None:
             if args.target == 'pyboard':
                 # run pyboard tests
-                test_dirs = ('basics', 'micropython', 'float', 'misc', 'extmod', 'pyb', 'pybnative', 'inlineasm')
+                test_dirs = ('basics', 'micropython', 'float', 'misc', 'stress', 'extmod', 'pyb', 'pybnative', 'inlineasm')
             elif args.target == 'esp8266':
                 test_dirs = ('basics', 'micropython', 'float', 'misc', 'extmod')
             elif args.target == 'wipy':
@@ -373,7 +373,7 @@ def main():
                 test_dirs = ('basics', 'micropython', 'misc', 'extmod', 'wipy')
             else:
                 # run PC tests
-                test_dirs = ('basics', 'micropython', 'float', 'import', 'io', 'misc', 'unicode', 'extmod', 'unix', 'cmdline')
+                test_dirs = ('basics', 'micropython', 'float', 'import', 'io', 'misc', 'stress', 'unicode', 'extmod', 'unix', 'cmdline')
         else:
             # run tests from these directories
             test_dirs = args.test_dirs

tests/stress/dict_copy.py

@@ -0,0 +1,7 @@
+# copying a large dictionary
+
+a = {i:2*i for i in range(1000)}
+b = a.copy()
+for i in range(1000):
+    print(i, b[i])
+print(len(b))

tests/stress/dict_create.py

@@ -0,0 +1,8 @@
+# create a large dictionary
+
+d = {}
+x = 1
+while x < 1000:
+    d[x] = x
+    x += 1
+print(d[500])

tests/stress/list_sort.py

@@ -0,0 +1,6 @@
+# test large list sorting (should not stack overflow)
+l = list(range(2000))
+l.sort()
+print(l[0], l[-1])
+l.sort(reverse=True)
+print(l[0], l[-1])