tests/cpydiff: Add cases for locals() discrepancies.

MicroPython doesn't maintain local symbolic environment, so any feature
depending on it won't work as expected.

tests/cpydiff/core_locals.py

@@ -0,0 +1,11 @@
+"""
+categories: Core,Runtime
+description: Local variables aren't included in locals() result
+cause: MicroPython doesn't maintain symbolic local environment, it is optimized to an array of slots. Thus, local variables can't be accessed by a name.
+workaround: Unknown
+"""
+def test():
+    val = 2
+    print(locals())
+
+test()

tests/cpydiff/core_locals_eval.py

@@ -0,0 +1,14 @@
+"""
+categories: Core,Runtime
+description: Code running in eval() function doesn't have access to local variables
+cause: MicroPython doesn't maintain symbolic local environment, it is optimized to an array of slots. Thus, local variables can't be accessed by a name. Effectively, ``eval(expr)`` in MicroPython is equivalent to ``eval(expr, globals(), globals())``.
+workaround: Unknown
+"""
+val = 1
+
+def test():
+    val = 2
+    print(val)
+    eval("print(val)")
+
+test()