Replace Travis/Appveyor CI with GitHub Action Workflow

.github/workflows/ci.yml

@@ -0,0 +1,56 @@
+name: Run TUF tests and linter
+
+on: [push, pull_request, workflow_dispatch]
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      # Run regular TUF tests on each OS/Python combination, plus special tests
+      # (sslib master) and linters on Linux/Python3.x only.
+      matrix:
+        python-version: [2.7, 3.6, 3.7, 3.8, 3.9]
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        toxenv: [py]
+        include:
+          - python-version: 3.x
+            os: ubuntu-latest
+            toxenv: with-sslib-master
+            experimental: true
+          # TODO: Change to 3.x once pylint fully supports Python 3.9
+          - python-version: 3.8
+            os: ubuntu-latest
+            toxenv: lint
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - name: Checkout TUF
+        uses: actions/checkout@v2
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Find pip cache dir
+        id: pip-cache
+        run: echo "::set-output name=dir::$(pip cache dir)"
+
+      - name: pip cache
+        uses: actions/cache@v2
+        with:
+          # Use the os dependent pip cache directory found above
+          path: ${{ steps.pip-cache.outputs.dir }}
+          # A match with 'key' counts as cache hit
+          key: ${{ runner.os }}-pip-${{ hashFiles('requirements*.txt') }}
+          # A match with 'restore-keys' is used as fallback
+          restore-keys: ${{ runner.os }}-pip-
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install tox
+
+      - name: Run tox
+        run: tox -e ${{ matrix.toxenv }}

README.md

@@ -1,9 +1,7 @@
 # <img src="https://cdn.rawgit.com/theupdateframework/artwork/3a649fa6/tuf-logo.svg" height="100" valign="middle" alt="TUF"/> A Framework for Securing Software Update Systems
 
-[![Travis-CI](https://travis-ci.com/theupdateframework/tuf.svg?branch=develop)](https://travis-ci.com/theupdateframework/tuf)
-[![Coveralls](https://coveralls.io/repos/theupdateframework/tuf/badge.svg?branch=develop)](https://coveralls.io/r/theupdateframework/tuf?branch=develop)
+![Build](https://github.com/theupdateframework/tuf/workflows/Run%20TUF%20tests%20and%20linter/badge.svg)
 ![Dependabot Status](https://api.dependabot.com/badges/status?host=github&repo=theupdateframework/tuf)
-[![FOSSA Status](https://app.fossa.com/api/projects/custom%2B162%2Fgithub.com%2Ftheupdateframework%2Ftuf.svg?type=shield)](https://app.fossa.com/projects/custom%2B162%2Fgithub.com%2Ftheupdateframework%2Ftuf?ref=badge_shield)
 [![CII](https://bestpractices.coreinfrastructure.org/projects/1351/badge)](https://bestpractices.coreinfrastructure.org/projects/1351)
 [![PyPI](https://img.shields.io/pypi/v/tuf)](https://pypi.org/project/tuf/)
 

docs/GOVERNANCE.md

@@ -27,7 +27,7 @@ guidelines](https://github.com/secure-systems-lab/code-style-guidelines), and
 must unit test any new software feature or change.  Submitted pull requests
 undergo review and automated testing, including, but not limited to:
 
-* Unit and build testing via [Travis CI](https://travis-ci.com/) and
+* Unit and build testing via [GitHub Actions](https://github.com/theupdateframework/tuf/actions) and
 [Tox](https://tox.readthedocs.io/en/latest/).
 * Static code analysis via [Pylint](https://www.pylint.org/) and
 [Bandit](https://wiki.openstack.org/wiki/Security/Projects/Bandit).

tests/test_updater.py

@@ -1344,10 +1344,12 @@ def test_6_download_target(self):
       self.repository_updater.download_target(targetinfo, bad_destination_directory)
 
     except OSError as e:
-      self.assertTrue(e.errno == errno.ENAMETOOLONG or e.errno == errno.ENOENT)
+      self.assertTrue(
+          e.errno in [errno.ENAMETOOLONG, errno.ENOENT, errno.EINVAL],
+          "wrong errno: " + str(e.errno))
 
     else:
-      self.fail('Expected an OSError of type ENAMETOOLONG or ENOENT')
+      self.fail('No OSError raised')
 
 
     # Test: Invalid arguments.

tox.ini

@@ -23,7 +23,8 @@ deps =
     # installation (see `skipsdist`), to get relative paths in coverage reports
     --editable {toxinidir}
 
-install_command = pip install --pre {opts} {packages}
+# FIXME: use legacy resolver because https://github.com/pypa/pip/issues/9215
+install_command = pip install --use-deprecated=legacy-resolver --pre {opts} {packages}
 
 
 # Develop test env to run tests against securesystemslib's master branch