diff --git a/.github/workflows/pipeline.yml b/.github/workflows/pipeline.yml
index 4cc51ecd..2b1f5b24 100644
--- a/.github/workflows/pipeline.yml
+++ b/.github/workflows/pipeline.yml
@@ -68,7 +68,7 @@ jobs:
 
       - name: Test
         run: |
-          python -m unittest discover -s tests
+          pytest tests -m "not slow"
 
       - name: Install pypa/build
         run: |
diff --git a/pyproject.toml b/pyproject.toml
index eab50479..d11219fe 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -42,6 +42,7 @@ dependencies = [
 testing = [
     "certifi", # tries to prevent certificate problems on windows
     "pytest",
+    "coverage",
     "pre-commit", # system tests run pre-commit
     "ax-platform >=0.3.5"
 ]
@@ -54,7 +55,6 @@ docs = [
     "sphinx_copybutton>=0.5.1",
     "sphinx-sitemap>=2.5.0",
 ]
-
 ax = [
     "ax-platform >=0.3.5"
 ]
@@ -78,3 +78,9 @@ line-length = 88
 testpaths = [
     "tests",
 ]
+pythonpath = [
+    "tests",
+]
+markers = [
+    "slow: marks tests as slow (deselect with '-m \"not slow\"')",
+]
diff --git a/tests/test_optimizer_behavior.py b/tests/test_optimizer_behavior.py
index acd54301..b0af2265 100644
--- a/tests/test_optimizer_behavior.py
+++ b/tests/test_optimizer_behavior.py
@@ -178,7 +178,7 @@ def optimizer(request):
 
 
 # %% Tests
-
+@pytest.mark.slow
 def test_convergence(optimization_problem: TestProblem, optimizer: OptimizerBase):
     # only test problems that the optimizer can handle. The rest of the tests
     # will be marked as passed
@@ -194,7 +194,7 @@ def test_convergence(optimization_problem: TestProblem, optimizer: OptimizerBase
         else:
             optimization_problem.test_if_solved(results, MOO_TEST_KWARGS)
 
-
+@pytest.mark.slow
 def test_from_initial_values(
     optimization_problem: TestProblem, optimizer: OptimizerBase
 ):
@@ -233,7 +233,7 @@ def __call__(self, results):
             raise RuntimeError("Max number of evaluations reached. Aborting!")
         self.n_calls += 1
 
-
+@pytest.mark.slow
 def test_resume_from_checkpoint(
     optimization_problem: TestProblem, optimizer: OptimizerBase
 ):