diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 06b266f5..9e20a923 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -4,15 +4,33 @@ jobs:
   run:
     runs-on: ubuntu-latest
     steps:
+      - uses: bazelbuild/setup-bazelisk@v2
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
       - name: Set up Python 3.10
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: '3.10'
       - name: Install dependencies
         run: pip install -r requirements.txt
-      - name: Run tests and collect coverage
-        run: pytest --cov app
-      - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v3
+      - name: give wrapper permission
+        run: chmod +x app/projectA/codecov_wrapper.sh
+      - name: run tests by bazel and generate coverage
+        run: |
+          python -m pip install --upgrade pip
+          pip install virtualenv
+          virtualenv venv
+          source venv/bin/activate
+          pip install codecov-cli
+          echo "$GCP_CREDENTIALS" > service.json
+          echo "-----"
+          bazel build //app/...
+          bazel coverage --run_under //app/projectA:codecov_wrapper.sh \
+            --test_output=all \
+            --action_env=GIT_DIR=${PWD}/$(git rev-parse --git-dir) \
+            --action_env=CODECOV_TOKEN=${{ secrets.CODECOV_TOKEN }} \
+            --remote_cache=https://storage.googleapis.com/bazel-test-dana \
+            --google_credentials=service.json \
+            --combined_report=lcov //app/...
+        env:
+          GCP_CREDENTIALS: ${{ secrets.GCP_CREDENTIALS }}
diff --git a/WORKSPACE.bazel b/WORKSPACE.bazel
new file mode 100644
index 00000000..e41b88a6
--- /dev/null
+++ b/WORKSPACE.bazel
@@ -0,0 +1,18 @@
+#https://github.com/bazelbuild/rules_python - for using py rules 
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
+http_archive(
+    name = "rules_python",
+    sha256 = "84aec9e21cc56fbc7f1335035a71c850d1b9b5cc6ff497306f84cced9a769841",
+    strip_prefix = "rules_python-0.23.1",
+    url = "https://github.com/bazelbuild/rules_python/releases/download/0.23.1/rules_python-0.23.1.tar.gz",
+)
+
+load("@rules_python//python:repositories.bzl", "py_repositories", "python_register_toolchains")
+
+py_repositories()
+
+python_register_toolchains(
+    name = "python39",
+    python_version = "3.9",
+    register_coverage_tool = True,
+)
\ No newline at end of file
diff --git a/app/projectA/BUILD.bazel b/app/projectA/BUILD.bazel
new file mode 100644
index 00000000..2bba0201
--- /dev/null
+++ b/app/projectA/BUILD.bazel
@@ -0,0 +1,15 @@
+py_library(
+    name="calculator",
+    srcs=["calculator.py"],
+
+)
+
+py_test(
+    name="test_calculator",
+    srcs=["test_calculator.py"],
+    deps = [
+        "//app/projectA:calculator",
+    ]
+)
+
+exports_files(["codecov_wrapper.sh"])
diff --git a/app/calculator.py b/app/projectA/calculator.py
similarity index 100%
rename from app/calculator.py
rename to app/projectA/calculator.py
diff --git a/app/projectA/codecov_wrapper.sh b/app/projectA/codecov_wrapper.sh
new file mode 100755
index 00000000..6129daf0
--- /dev/null
+++ b/app/projectA/codecov_wrapper.sh
@@ -0,0 +1,16 @@
+#/bin/bash
+
+# `bazel coverage --run_under foo :bar` basically translates to:
+#     foo pytest --cov bar/src/a.py bar/src/b.py
+# We want to run that `pytest` command unmodified, as below:
+"$@"
+
+# codecov doesn't recognise pylcov.dat as a coverage report, renaming it to lcov.dat so codecov can acknowledge it  
+mv $COVERAGE_DIR/pylcov.dat $COVERAGE_DIR/lcov.dat
+
+# uploading coverage
+codecovcli -v create-commit -t $CODECOV_TOKEN
+codecovcli -v create-report -t $CODECOV_TOKEN
+codecovcli -v do-upload -t $CODECOV_TOKEN -s $COVERAGE_DIR
+
+
diff --git a/app/projectA/test_calculator.py b/app/projectA/test_calculator.py
new file mode 100644
index 00000000..be2c1611
--- /dev/null
+++ b/app/projectA/test_calculator.py
@@ -0,0 +1,40 @@
+
+from app.projectA.calculator import Calculator
+
+import unittest
+
+
+
+class TestMethods(unittest.TestCase):
+    def test_add(self):
+        self.assertEqual(True, True)
+    
+    def test_add(self):
+        self.assertEqual(Calculator.add(1, 2), 3.0)
+        self.assertEqual(Calculator.add(1.0, 2.0), 3.0)
+        self.assertEqual(Calculator.add(0, 2.0), 2.0)
+        self.assertEqual(Calculator.add(2.0, 0), 2.0)
+        self.assertEqual(Calculator.add(-4, 2.0), -2.0)
+
+    def test_subtract(self):
+        self.assertEqual(Calculator.subtract(1, 2) , -1.0)
+        self.assertEqual(Calculator.subtract(2, 1) , 1.0)
+        self.assertEqual(Calculator.subtract(1.0, 2.0) , -1.0)
+        self.assertEqual(Calculator.subtract(0, 2.0) , -2.0)
+        self.assertEqual(Calculator.subtract(2.0, 0.0) , 2.0)
+        self.assertEqual(Calculator.subtract(-4, 2.0) , -6.0)
+
+    def test_multiply(self):
+        self.assertEqual(Calculator.multiply(1, 2) , 2.0)
+        self.assertEqual(Calculator.multiply(1.0, 2.0) , 2.0)
+        self.assertEqual(Calculator.multiply(0, 2.0) , 0.0)
+        self.assertEqual(Calculator.multiply(2.0, 0.0) , 0.0)
+        self.assertEqual(Calculator.multiply(-4, 2.0) , -8.0)
+
+    def test_divide(self):
+        self.assertEqual(Calculator.divide(1.0, 2.0) , 0.5)
+        self.assertEqual(Calculator.divide(0, 2.0) , 0)
+        self.assertEqual(Calculator.divide(-4, 2.0) , -2.0)
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/app/projectB/BUILD.bazel b/app/projectB/BUILD.bazel
new file mode 100644
index 00000000..3c65aa33
--- /dev/null
+++ b/app/projectB/BUILD.bazel
@@ -0,0 +1,15 @@
+py_library(
+    name="adder",
+    srcs=["adder.py"],
+
+)
+
+py_test(
+    name="test_adder",
+    srcs=["test_adder.py"],
+    deps = [
+        "//app/projectB:adder",
+    ]
+)
+
+exports_files(["codecov_wrapper.sh"])
diff --git a/app/projectB/adder.py b/app/projectB/adder.py
new file mode 100644
index 00000000..57f0dc95
--- /dev/null
+++ b/app/projectB/adder.py
@@ -0,0 +1,3 @@
+class Adder:
+    def add(self, x, y):
+        return x + y
\ No newline at end of file
diff --git a/app/projectB/codecov_wrapper.sh b/app/projectB/codecov_wrapper.sh
new file mode 100755
index 00000000..6129daf0
--- /dev/null
+++ b/app/projectB/codecov_wrapper.sh
@@ -0,0 +1,16 @@
+#/bin/bash
+
+# `bazel coverage --run_under foo :bar` basically translates to:
+#     foo pytest --cov bar/src/a.py bar/src/b.py
+# We want to run that `pytest` command unmodified, as below:
+"$@"
+
+# codecov doesn't recognise pylcov.dat as a coverage report, renaming it to lcov.dat so codecov can acknowledge it  
+mv $COVERAGE_DIR/pylcov.dat $COVERAGE_DIR/lcov.dat
+
+# uploading coverage
+codecovcli -v create-commit -t $CODECOV_TOKEN
+codecovcli -v create-report -t $CODECOV_TOKEN
+codecovcli -v do-upload -t $CODECOV_TOKEN -s $COVERAGE_DIR
+
+
diff --git a/app/projectB/test_adder.py b/app/projectB/test_adder.py
new file mode 100644
index 00000000..6aea25c9
--- /dev/null
+++ b/app/projectB/test_adder.py
@@ -0,0 +1,11 @@
+import unittest
+
+from app.projectB.adder import Adder
+
+
+class TestAdder(unittest.TestCase):
+    def test_adder(self):
+        assert 2 + 3.0 == Adder().add(2, 3)
+
+if __name__ == "__main__":
+    unittest.main()
\ No newline at end of file
diff --git a/app/test_calculator.py b/app/test_calculator.py
deleted file mode 100644
index 8b61b6b3..00000000
--- a/app/test_calculator.py
+++ /dev/null
@@ -1,32 +0,0 @@
-from .calculator import Calculator
-
-
-def test_add():
-    assert 1 == 1
-
-# def test_subtract():
-#     assert Calculator.subtract(1, 2) == -1.0
-#     assert Calculator.subtract(2, 1) == 1.0
-#     assert Calculator.subtract(1.0, 2.0) == -1.0
-#     assert Calculator.subtract(0, 2.0) == -2.0
-#     assert Calculator.subtract(2.0, 0.0) == 2.0
-#     assert Calculator.subtract(-4, 2.0) == -6.0
-
-# def test_multiply():
-#     assert Calculator.multiply(1, 2) == 2.0
-#     assert Calculator.multiply(1.0, 2.0) == 2.0
-#     assert Calculator.multiply(0, 2.0) == 0.0
-#     assert Calculator.multiply(2.0, 0.0) == 0.0
-#     assert Calculator.multiply(-4, 2.0) == -8.0
-
-def test_trivial():
-    assert True
-
-# def test_divide():
-#     # assert Calculator.divide(1, 2) == 0.5
-#     assert Calculator.divide(1.0, 2.0) == 0.5
-#     assert Calculator.divide(0, 2.0) == 0
-#     assert Calculator.divide(-4, 2.0) == -2.0
-#     # assert Calculator.divide(2.0, 0.0) == 'Cannot divide by 0'
-
-