diff --git a/.github/workflows/verification.yml b/.github/workflows/verification.yml
new file mode 100644
index 0000000..de6e1a3
--- /dev/null
+++ b/.github/workflows/verification.yml
@@ -0,0 +1,23 @@
+name: Static Checks
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: '3.9'
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install .[contrib]
+    - name: Lint with flake8
+      run: |
+        flake8 tardis tests setup.py
+    - name: Format with black
+      run: |
+        black tardis tests setup.py --diff --check --target-version py36
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index d7679cc..0000000
--- a/.travis.yml
+++ /dev/null
@@ -1,37 +0,0 @@
-language: python
-
-python:
-  - "3.6"
-  - "3.7"
-  - "3.8"
-  - "3.9"
-  - "nightly" # currently points to 3.8-dev
-  - "pypy3"
-
-os:
-  - linux
-
-matrix:
-  allow_failures:
-  - python: "nightly"
-  - python: "pypy3"
-  include:
-    - python: 3.7
-      name: Style
-      dist: xenial
-      script:
-        - python -m flake8 tardis tests setup.py
-        - python -m black --target-version py36 --check tardis/ tests/ setup.py
-  fast_finish: true
-
-install:
-  - pip install codecov
-  - pip install coverage
-  - pip install .[contrib]
-  - pip install git+https://github.com/MatterMiners/cobald.git
-
-script: coverage run setup.py test
-
-after_success:
-  - coverage report
-  - codecov
diff --git a/README.md b/README.md
index 880d4f7..256ddd3 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,5 @@
-[![Build Status](https://travis-ci.org/MatterMiners/tardis.svg?branch=master)](https://travis-ci.org/MatterMiners/tardis)
+[![Build Status](https://github.com/MatterMiners/tardis/actions/workflows/unittests.yml/badge.svg)](https://github.com/MatterMiners/tardis/actions/workflows/unittests.yml)
+[![Verification](https://github.com/MatterMiners/tardis/actions/workflows/verification.yml/badge.svg)](https://github.com/MatterMiners/tardis/actions/workflows/verification.yml)
 [![codecov](https://codecov.io/gh/MatterMiners/tardis/branch/master/graph/badge.svg)](https://codecov.io/gh/MatterMiners/tardis)
 [![Documentation Status](https://readthedocs.org/projects/cobald-tardis/badge/?version=latest)](https://cobald-tardis.readthedocs.io/en/latest/?badge=latest)
 [![Development and Help Chat](https://badges.gitter.im/MatterMiners.png)](https://gitter.im/MatterMiners/community)
diff --git a/docs/source/changelog.rst b/docs/source/changelog.rst
index 1f95158..c8aad5a 100644
--- a/docs/source/changelog.rst
+++ b/docs/source/changelog.rst
@@ -1,4 +1,4 @@
-.. Created by changelog.py at 2021-03-23, command
+.. Created by changelog.py at 2021-03-24, command
    '/Users/giffler/.cache/pre-commit/repor6pnmwlm/py_env-python3.9/bin/changelog docs/source/changes compile --output=docs/source/changelog.rst'
    based on the format of 'https://keepachangelog.com/'
 
@@ -6,7 +6,7 @@
 CHANGELOG
 #########
 
-[Unreleased] - 2021-03-23
+[Unreleased] - 2021-03-24
 =========================
 
 Added
@@ -17,6 +17,7 @@ Added
 Fixed
 -----
 
+* Fixes a bug that get_resource_ratios raised a ValueError
 * Fixes a bug that the drone_minimum_lifetime parameter is not working as described in the documentation
 * Fixes a bug in the HTCondor Site Adapter which leads to wrong requirements when using non HTCondor OBS
 
diff --git a/docs/source/changes/175.fix_resource_ratios.yaml b/docs/source/changes/175.fix_resource_ratios.yaml
new file mode 100644
index 0000000..1ba3409
--- /dev/null
+++ b/docs/source/changes/175.fix_resource_ratios.yaml
@@ -0,0 +1,10 @@
+category: fixed
+summary: "Fixes a bug that get_resource_ratios raised a ValueError"
+description: |
+    In case one of the resource ratios is `undefined` or even has the value `error`
+    a `ValueError` or `TypeError` could occur. In case one of those errors occurs,
+    an empty list is returned.
+pull requests:
+  - 175
+issues:
+  - 168
diff --git a/setup.py b/setup.py
index 615818b..3a46a9c 100644
--- a/setup.py
+++ b/setup.py
@@ -68,7 +68,8 @@ setup(
     extras_require={
         "docs": ["sphinx", "sphinx_rtd_theme", "sphinxcontrib-contentui"],
         "test": TESTS_REQUIRE,
-        "contrib": ["flake8", "flake8-bugbear", "black"] + TESTS_REQUIRE,
+        "contrib": ["flake8", "flake8-bugbear", "black; implementation_name=='cpython'"]
+        + TESTS_REQUIRE,
     },
     tests_require=TESTS_REQUIRE,
     zip_safe=False,
diff --git a/tardis/adapters/batchsystems/htcondor.py b/tardis/adapters/batchsystems/htcondor.py
index 0bb702b..67ec25b 100644
--- a/tardis/adapters/batchsystems/htcondor.py
+++ b/tardis/adapters/batchsystems/htcondor.py
@@ -172,14 +172,13 @@ class HTCondorAdapter(BatchSystemAdapter):
         await self._htcondor_status.update_status()
         try:
             htcondor_status = self._htcondor_status[drone_uuid]
-        except KeyError:
-            return {}
-        else:
-            return (
+            return [
                 float(value)
                 for key, value in htcondor_status.items()
                 if key in self.ratios.keys()
-            )
+            ]
+        except (KeyError, ValueError, TypeError):
+            return []
 
     async def get_allocation(self, drone_uuid: str) -> float:
         """

diff --git a/.github/workflows/unittests.yml b/.github/workflows/unittests.yml
new file mode 100644
index 0000000..c38701a
--- /dev/null
+++ b/.github/workflows/unittests.yml
@@ -0,0 +1,27 @@
+name: Unit Tests
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ['3.6', '3.7', '3.8', '3.9']
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install .[contrib]
+        pip install coverage codecov
+    - name: Test with unittest
+      run: |
+        coverage run -m unittest -v
+    - name: Upload coverage to Codecov
+      uses: codecov/codecov-action@v1
diff --git a/tests/adapters_t/batchsystems_t/test_htcondor.py b/tests/adapters_t/batchsystems_t/test_htcondor.py
index cc4c41f..0a0e2a8 100644
--- a/tests/adapters_t/batchsystems_t/test_htcondor.py
+++ b/tests/adapters_t/batchsystems_t/test_htcondor.py
@@ -57,6 +57,8 @@ class TestHTCondorAdapter(TestCase):
                 f"test_drained\tslot1@test\tDrained\tIdle\tundefined\t{self.cpu_ratio}\t{self.memory_ratio}",  # noqa: B950
                 f"test_owner\tslot1@test\tOwner\tIdle\tundefined\t{self.cpu_ratio}\t{self.memory_ratio}",  # noqa: B950
                 f"test_uuid_plus\tslot1@test_uuid@test\tUnclaimed\tIdle\ttest_uuid\t{self.cpu_ratio}\t{self.memory_ratio}",  # noqa: B950
+                f"test_undefined\tslot1@test\tUnclaimed\tIdle\tundefined\tundefined\t{self.memory_ratio}",  # noqa: B950
+                f"test_error\tslot1@test\tUnclaimed\tIdle\tundefined\terror\t{self.memory_ratio}",  # noqa: B950
                 "exoscale-26d361290f\tslot1@exoscale-26d361290f\tUnclaimed\tIdle\tundefined\t0.125\t0.125",  # noqa: B950
             ]
         )
@@ -151,12 +153,31 @@ class TestHTCondorAdapter(TestCase):
             [self.cpu_ratio, self.memory_ratio],
         )
         self.mock_async_run_command.assert_called_with(self.command)
+        self.mock_async_run_command.reset_mock()
 
         self.assertEqual(
             run_async(
                 self.htcondor_adapter.get_resource_ratios, drone_uuid="not_exists"
             ),
-            {},
+            [],
+        )
+        self.mock_async_run_command.assert_not_called()
+        self.mock_async_run_command.reset_mock()
+
+        self.assertEqual(
+            run_async(
+                self.htcondor_adapter.get_resource_ratios, drone_uuid="test_undefined"
+            ),
+            [],
+        )
+        self.mock_async_run_command.assert_not_called()
+        self.mock_async_run_command.reset_mock()
+
+        self.assertEqual(
+            run_async(
+                self.htcondor_adapter.get_resource_ratios, drone_uuid="test_error"
+            ),
+            [],
         )
 
     def test_get_resource_ratios_without_options(self):

Move CI to GitHub actions
Move CI to GitHub actions instead of using `travis.org`, which is recently quite slow.
tests/adapters_t/batchsystems_t/test_htcondor.py::TestHTCondorAdapter::test_get_resource_ratios
tests/adapters_t/batchsystems_t/test_htcondor.py::TestHTCondorAdapter::test_disintegrate_machine tests/adapters_t/batchsystems_t/test_htcondor.py::TestHTCondorAdapter::test_drain_machine tests/adapters_t/batchsystems_t/test_htcondor.py::TestHTCondorAdapter::test_drain_machine_without_options tests/adapters_t/batchsystems_t/test_htcondor.py::TestHTCondorAdapter::test_get_allocation tests/adapters_t/batchsystems_t/test_htcondor.py::TestHTCondorAdapter::test_get_machine_status tests/adapters_t/batchsystems_t/test_htcondor.py::TestHTCondorAdapter::test_get_resource_ratios_without_options tests/adapters_t/batchsystems_t/test_htcondor.py::TestHTCondorAdapter::test_get_utilisation tests/adapters_t/batchsystems_t/test_htcondor.py::TestHTCondorAdapter::test_integrate_machine tests/adapters_t/batchsystems_t/test_htcondor.py::TestHTCondorAdapter::test_machine_meta_data_translation_mapping