Add testcase for logging module.

tests/snippets/test_logging.py

@@ -0,0 +1,14 @@
+
+import io
+import sys
+
+f = io.StringIO()
+sys.stderr = f
+
+import logging
+
+logging.error('WOOT')
+logging.warning('WARN')
+
+print(f.getvalue())
+

vm/src/obj/objframe.rs

@@ -5,7 +5,7 @@
 use super::objcode::PyCodeRef;
 use super::objdict::PyDictRef;
 use crate::frame::FrameRef;
-use crate::pyobject::{PyContext, PyResult};
+use crate::pyobject::{PyContext, PyObjectRef, PyResult};
 use crate::vm::VirtualMachine;
 
 pub fn init(context: &PyContext) {
@@ -13,7 +13,10 @@ pub fn init(context: &PyContext) {
         "__new__" => context.new_rustfunc(FrameRef::new),
         "__repr__" => context.new_rustfunc(FrameRef::repr),
         "f_locals" => context.new_property(FrameRef::flocals),
+        "f_globals" => context.new_property(FrameRef::f_globals),
         "f_code" => context.new_property(FrameRef::fcode),
+        "f_back" => context.new_property(FrameRef::f_back),
+        "f_lasti" => context.new_property(FrameRef::f_lasti),
     });
 }
 
@@ -27,6 +30,10 @@ impl FrameRef {
         "<frame object at .. >".to_string()
     }
 
+    fn f_globals(self, _vm: &VirtualMachine) -> PyDictRef {
+        self.scope.globals.clone()
+    }
+
     fn flocals(self, _vm: &VirtualMachine) -> PyDictRef {
         self.scope.get_locals()
     }
@@ -34,4 +41,13 @@ impl FrameRef {
     fn fcode(self, vm: &VirtualMachine) -> PyCodeRef {
         vm.ctx.new_code_object(self.code.clone())
     }
+
+    fn f_back(self, vm: &VirtualMachine) -> PyObjectRef {
+        // TODO: how to retrieve the upper stack frame??
+        vm.ctx.none()
+    }
+
+    fn f_lasti(self, vm: &VirtualMachine) -> PyObjectRef {
+        vm.ctx.new_int(*self.lasti.borrow())
+    }
 }