diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index d6b1ab11..ce65c64f 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -16,6 +16,7 @@ jobs:
 
     env:
       DEBUG_TEST_PYFLYBY: 1
+      ENVNAME: ${{matrix.os}}-${{matrix.python-version}}
 
     steps:
     - uses: actions/checkout@v3
@@ -33,7 +34,7 @@ jobs:
       if: ${{ matrix.python-version != '2.7'}}
       run: |
         python -m pip install --upgrade pip setuptools wheel
-        python -m pip install --upgrade "pexpect>=3.3" 'pytest<7' rlipython ipykernel==5.4.3 requests jupyter flaky 'notebook<6.1' 'prompt_toolkit<3.0.15' wheel 'jupyter_console>=6.2' 'pytest-cov<3' ipython 'coverage<6.3'
+        python -m pip install --upgrade "pexpect>=3.3" 'pytest<7' rlipython ipykernel==5.4.3 requests jupyter flaky 'notebook<6.1' 'prompt_toolkit<3.0.15' wheel 'jupyter_console>=6.2' 'pytest-cov<3' ipython 'coverage<6.3' pytest-json-report
         pip install -e .
     - name: test release build
       run: |
@@ -41,9 +42,25 @@ jobs:
     - name: compileall
       run: |
         python -We:invalid -m compileall -f -q lib/ etc/;
-    - name: pytest
+    - name: pytest Python 2 or Mac OS
+      if: ${{ matrix.python-version == '2.7' || matrix.os == 'macos-latest'}}
+      # json report can't be installed on Py2, and make macos super slow.
       run: |
         python -m pytest --cov=pyflyby --cov-report=xml --doctest-modules --maxfail=3 lib tests
+    - name: pytest Python 3
+      if: ${{ matrix.python-version != '2.7' && matrix.os != 'macos-latest'  }}
+      run: |
+        python -m pytest --cov=pyflyby --cov-report=xml\
+               --doctest-modules\
+               --maxfail=3\
+               --json-report\
+               --json-report-file=report-${ENVNAME}.json\
+               lib tests
+    - uses: actions/upload-artifact@v3
+      name: upload pytest timing reports as json
+      with:
+        path: |
+          ./report-*.json
     - uses: codecov/codecov-action@v2
     - name: Build docs
       if: ${{ matrix.python-version == '3.10'}}
diff --git a/codecov.yml b/codecov.yml
new file mode 100644
index 00000000..27f9ddd3
--- /dev/null
+++ b/codecov.yml
@@ -0,0 +1,16 @@
+coverage:
+  status:
+    project:
+      default:
+        threshold: 1%
+        target: 70%
+    patch:
+      default:
+        threshold: 1%
+        target: 0%
+codecov:
+  notify:
+    after_n_builds: 6
+comment:
+  require_changes: true  # if true: only post the PR comment if coverage changes
+  after_n_builds: 6
diff --git a/tests/test_interactive.py b/tests/test_interactive.py
index 75ebc902..0d46704b 100644
--- a/tests/test_interactive.py
+++ b/tests/test_interactive.py
@@ -4183,11 +4183,44 @@ def test_debug_postmortem_tab_completion_1(frontend):
     """, frontend=frontend)
 
 
-@pytest.mark.xfail(
+@pytest.mark.skipif(
+    sys.version_info[0] == 2,
+    reason="[PYFLYBY] import base64 is not triggered at the same time depending on python versions",
+)
+def test_debug_namespace_1_py3(frontend):
+    # Verify that autoimporting and tab completion happen in the local
+    # namespace.
+    # In this example, in the local namespace, 'base64' is a variable (which
+    # is a string), and shouldn't refer to the global 'base64'.
+    ipython("""
+        In [1]: import pyflyby; pyflyby.enable_auto_importer()
+        In [2]: def foo(x, base64):
+           ...:     return x / base64
+           ...:
+        In [3]: foo("Lexington", "atlantic")
+        ---------------------------------------------------------------------------
+        TypeError                                 Traceback (most recent call last)
+        ....
+        TypeError: unsupported operand type(s) for /: 'str' and 'str'
+        In [4]: %debug
+        ....
+        ipdb> print(base64.cap\titalize() + b64deco\tde("UGFjaWZpYw==").decode('utf-8'))
+        [PYFLYBY] from base64 import b64decode
+        AtlanticPacific
+        ipdb> p b64deco\tde("Q29udGluZW50YWw=")
+        b'Continental'
+        ipdb> q
+        In [5]: base64.b64de\t
+        In [5]: base64.b64decode("SGlsbA==") + b64deco\tde("TGFrZQ==")
+        [PYFLYBY] from base64 import b64decode
+        Out[5]: b'HillLake'
+    """, frontend=frontend)
+
+@pytest.mark.skipif(
     sys.version_info[0] == 3,
     reason="[PYFLYBY] import base64 is not triggered at the same time depending on python versions",
 )
-def test_debug_namespace_1(frontend):
+def test_debug_namespace_1_py2(frontend):
     # Verify that autoimporting and tab completion happen in the local
     # namespace.
     # In this example, in the local namespace, 'base64' is a variable (which