diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index fffc758..d1e8118 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -23,11 +23,10 @@ jobs:
     - shell: bash -l {0}
       id: fetch-release
       run: |
-        python -m pip install packaging
         python fetch_release.py ${{ github.event.inputs.version }}
 
     - name: Release
-      uses: softprops/action-gh-release@v1
+      uses: softprops/action-gh-release@v2.2.0
       if: steps.fetch-release.outputs.MICROMAMBA_NEW_VERSION == 'true'
       with:
         name: "micromamba ${{ steps.fetch-release.outputs.MICROMAMBA_VERSION }}"
diff --git a/.github/workflows/test_fetch_release.yml b/.github/workflows/test_fetch_release.yml
new file mode 100644
index 0000000..c102fce
--- /dev/null
+++ b/.github/workflows/test_fetch_release.yml
@@ -0,0 +1,23 @@
+name: "Test fetching releases from Anaconda"
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  test_fetch_release:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: mamba-org/setup-micromamba@v1
+      with:
+        environment-file: environment.yml
+        create-args: pytest
+    - name: Add micromamba to GITHUB_PATH
+      run: echo "${HOME}/micromamba-bin" >> "$GITHUB_PATH"
+
+    - shell: bash -l {0}
+      id: fetch-release
+      run: |
+        python -m pytest tests/test_fetch_release.py -v --exitfirst
diff --git a/.github/workflows/test.yml b/.github/workflows/test_install.yml
similarity index 100%
rename from .github/workflows/test.yml
rename to .github/workflows/test_install.yml
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..05bfce0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,7 @@
+# Python caches
+*.pyc
+.pytest_cache/
+__pycache__
+
+# Generated files from tests
+*.tar.bz2
diff --git a/environment.yml b/environment.yml
index afedb0b..e7679e6 100644
--- a/environment.yml
+++ b/environment.yml
@@ -2,6 +2,7 @@ name: fetch-release-env
 channels:
   - conda-forge
 dependencies:
+  - packaging
   - python
   - requests
   - rich
diff --git a/fetch_release.py b/fetch_release.py
index 100efe2..0511d7f 100644
--- a/fetch_release.py
+++ b/fetch_release.py
@@ -72,6 +72,7 @@ def get_micromamba(version, use_default_version):
     build = max(all_build)
 
     print(f"Existing versions: {existing_tags}")
+    print(f"Checking {version}-{build}")
     if f"{version}-{build}" in existing_tags:
         print("Tag already exists, skipping")
         set_output("MICROMAMBA_NEW_VERSION", "false")
@@ -150,7 +151,7 @@ def get_micromamba(version, use_default_version):
     else:
         set_output("MICROMAMBA_NEW_PRERELEASE", "true")
 
-    if is_stable and v.major == 2:
+    if is_stable and v.major >= 2:
         set_output("MICROMAMBA_LATEST", "true")
     else:
         set_output("MICROMAMBA_LATEST", "false")
diff --git a/tests/test_fetch_release.py b/tests/test_fetch_release.py
new file mode 100644
index 0000000..26e4ce1
--- /dev/null
+++ b/tests/test_fetch_release.py
@@ -0,0 +1,377 @@
+import hashlib
+import pytest
+import requests
+import time
+
+from unittest.mock import patch, MagicMock
+
+
+# TODO do this more elegantly?
+# Put fetch_release in a py folder for example?
+import os
+import sys
+sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))
+
+import fetch_release
+
+@pytest.fixture(scope="module")
+def retry_config():
+    """
+    Fixture to define retry configuration.
+    """
+    return {
+        'max_retries': 1, # TODO set to 3 later?
+        'retry_delay': 5  # Delay between retries in seconds
+    }
+
+def get_output_value(name):
+    """
+    Retrieve the value of a variable from the GITHUB_OUTPUT file.
+    """
+    github_output_path = os.environ.get("GITHUB_OUTPUT")
+
+    if github_output_path and os.path.exists(github_output_path):
+        with open(github_output_path, "r") as f:
+            for line in f:
+                # Each line is in the form 'name=value'
+                if line.startswith(name + "="):
+                    return line.split("=", 1)[1].strip()  # Return the value after '='
+    return None
+
+def test_get_all_tags_github(retry_config):
+    """
+    Test getting all GitHub tags using the GitHub API.
+    """
+    max_retries = retry_config['max_retries']
+    retry_delay = retry_config['retry_delay']
+
+    for _ in range(max_retries):
+        try:
+            tags = fetch_release.get_all_tags_github()
+            # Tags list for a minimal tags check
+            tags_to_check = ["2.0.5-0", "2.0.5.rc0-0", "1.5.12-0"]
+            assert isinstance(tags, set)
+            assert len(tags) >= 30
+            assert set(tags_to_check).issubset(tags), f"Not all tags are in the set: {tags_to_check}"
+            print("Fetched GitHub tags:", tags)
+            return
+        except requests.exceptions.RequestException as e:
+            print(f"Error fetching tags, retrying... {e}")
+            time.sleep(retry_delay)
+
+    pytest.fail("Failed to fetch GitHub tags after multiple retries.")
+
+
+@pytest.mark.parametrize("version", ("latest", "2.0.5", "1.5.9", "2.0.5.rc0", "2.0.4alpha1"))
+@pytest.mark.parametrize("use_default_version", (False, True))
+def test_get_micromamba_existing_version(retry_config, version, use_default_version):
+    """
+    Test fetching existing micromamba stable version.
+    """
+    max_retries = retry_config['max_retries']
+    retry_delay = retry_config['retry_delay']
+
+    for _ in range(max_retries):
+        try:
+            fetch_release.get_micromamba(version, use_default_version)
+            assert get_output_value("MICROMAMBA_NEW_VERSION") == "false"
+            assert get_output_value("MICROMAMBA_NEW_PRERELEASE") == None
+            assert get_output_value("MICROMAMBA_LATEST") == None
+            assert get_output_value("MICROMAMBA_VERSION") == None
+            print(f"Fetched micromamba release {version} successfully.")
+            return
+        except requests.exceptions.RequestException as e:
+            print(f"Error fetching micromamba release, retrying... {e}")
+            time.sleep(retry_delay)
+
+    pytest.fail(f"Failed to fetch micromamba release info after multiple retries.")
+
+@pytest.mark.parametrize("use_default_version", (False, True))
+def test_get_micromamba_non_existing_version(use_default_version):
+    """
+    Test fetching non existing micromamba version.
+    """
+
+    with pytest.raises(requests.exceptions.HTTPError):
+        fetch_release.get_micromamba("9.10.5", use_default_version)
+
+#TODO mock test for non existing versions => new_version_1_x, new_version_2_x, new_prerelease
+
+@pytest.fixture
+def mock_github_tags():
+    """Mock GitHub tags to simulate existing tags."""
+    with patch('fetch_release.get_all_tags_github') as mock:
+        mock.return_value = {"2.0.5-0"}
+        yield mock
+
+@pytest.fixture
+def mock_anaconda_api():
+    """Mock Anaconda.org API response."""
+    with patch('fetch_release.requests.get') as mock:
+        # Simulate a new version available
+        mock.status_code = 200
+        #mock.raise_for_status = MagicMock()
+
+        mocked_content = b"some random binary data representing a tar.bz2 file"
+        mock.content = mocked_content
+
+        sha256 = hashlib.sha256()
+        sha256.update(mocked_content)
+        computed_checksum = sha256.hexdigest()
+
+        mock.json.return_value = {
+            "distributions": [
+                {
+                    "attrs": {
+                        "subdir": "linux-64",
+                        "build_number": 1
+                    },
+                    "download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/linux-64/micromamba-10.11.12-1.tar.bz2",
+                    "sha256": computed_checksum,
+                    "basename": "linux-64/micromamba-10.11.12-linux-64.tar.bz2",
+                    "version": "10.11.12"
+                },
+                {
+                    "attrs": {
+                        "subdir": "linux-aarch64",
+                        "build_number": 1
+                    },
+                    "download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/linux-aarch64/micromamba-10.11.12-1.tar.bz2",
+                    "sha256": computed_checksum,
+                    "basename": "linux-aarch64/micromamba-10.11.12-linux-aarch64.tar.bz2",
+                    "version": "10.11.12"
+                },
+                {
+                    "attrs": {
+                        "subdir": "linux-ppc64le",
+                        "build_number": 1
+                    },
+                    "download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/linux-ppc64le/micromamba-10.11.12-1.tar.bz2",
+                    "sha256": computed_checksum,
+                    "basename": "linux-ppc64le/micromamba-10.11.12-linux-ppc64le.tar.bz2",
+                    "version": "10.11.12"
+                },
+                {
+                    "attrs": {
+                        "subdir": "win-64",
+                        "build_number": 1
+                    },
+                    "download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/win-64/micromamba-10.11.12-1.tar.bz2",
+                    "sha256": computed_checksum,
+                    "basename": "win-64/micromamba-10.11.12-win-64.tar.bz2",
+                    "version": "10.11.12"
+                },
+                {
+                    "attrs": {
+                        "subdir": "osx-64",
+                        "build_number": 1
+                    },
+                    "download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/osx-64/micromamba-10.11.12-1.tar.bz2",
+                    "sha256": computed_checksum,
+                    "basename": "osx-64/micromamba-10.11.12-osx-64.tar.bz2",
+                    "version": "10.11.12"
+                },
+                {
+                    "attrs": {
+                        "subdir": "osx-arm64",
+                        "build_number": 1
+                    },
+                    "download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/osx-arm64/micromamba-10.11.12-1.tar.bz2",
+                    "sha256": computed_checksum,
+                    "basename": "osx-arm64/micromamba-10.11.12-osx-arm64.tar.bz2",
+                    "version": "10.11.12"
+                }
+            ]
+        }
+
+        yield mock
+
+
+@pytest.fixture
+def mock_check_call():
+    """Mock subprocess.check_call"""
+    with patch('fetch_release.subprocess.check_call') as mock:
+        mock.return_value = None
+        yield mock
+
+@pytest.fixture
+def mock_copyfile():
+    """Mock subprocess.check_call"""
+    with patch('fetch_release.shutil.copyfile') as mock:
+        #mock.return_value = None
+        def mock_copyfile_side_effect(*args, **kwargs): #src=None, dst=None, follow_symlinks=True):
+            # Simulate that the source file exists
+            # TODO use different versions and subdirs
+            #if src == 'micromamba-10.11.12-1-linux-64/bin/micromamba':
+                ## Simulate successful copy operation
+                #assert dst == 'releases/micromamba-linux-64'
+            #else:
+            if not args and not kwargs:
+                raise FileNotFoundError(f"File {src} not found")
+
+        mock.side_effect = mock_copyfile_side_effect
+
+        yield mock
+
+#@patch('requests.get')
+#@patch("subprocess.check_call")
+#@patch("shutil.copyfile")
+def test_get_micromamba_new_2_x_version(mock_github_tags, mock_anaconda_api, mock_check_call, mock_copyfile):
+    # Create a mock response object for get_all_tags_github (GitHub API)
+    #mock_github_response = MagicMock()
+    #mock_github_response.status_code = 200
+    #mock_github_response.raise_for_status = MagicMock()
+    #mock_github_response.json.return_value = [
+        #{"name": "2.0.5-0"},
+        #{"name": "latest"},
+    #]
+
+    # Create a mock response object for the Anaconda API (Anaconda API)
+    #mock_anaconda_response = MagicMock()
+    #mock_anaconda_response.status_code = 200
+    #mock_anaconda_response.raise_for_status = MagicMock()
+
+    ## Mock the response from the Anaconda API
+    #mock_response = MagicMock()
+    #mock_response.status_code = 200
+    #mock_response.raise_for_status = MagicMock()
+
+    # Mock request content to return a byte string
+    #mocked_content = b"some random binary data representing a tar.bz2 file"
+    #mock_response.content = mocked_content
+
+    #sha256 = hashlib.sha256()
+    #sha256.update(mocked_content)
+    #computed_checksum = sha256.hexdigest()
+
+    #mock_response.json.return_value = {
+        #"distributions": [
+            #{
+                #"attrs": {
+                    #"subdir": "linux-64",
+                    #"build_number": 1
+                #},
+                #"download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/linux-64/micromamba-10.11.12-1.tar.bz2",
+                #"sha256": computed_checksum,
+                #"basename": "linux-64/micromamba-10.11.12-linux-64.tar.bz2",
+                #"version": "10.11.12"
+            #},
+            #{
+                #"attrs": {
+                    #"subdir": "linux-aarch64",
+                    #"build_number": 1
+                #},
+                #"download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/linux-aarch64/micromamba-10.11.12-1.tar.bz2",
+                #"sha256": computed_checksum,
+                #"basename": "linux-aarch64/micromamba-10.11.12-linux-aarch64.tar.bz2",
+                #"version": "10.11.12"
+            #},
+            #{
+                #"attrs": {
+                    #"subdir": "linux-ppc64le",
+                    #"build_number": 1
+                #},
+                #"download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/linux-ppc64le/micromamba-10.11.12-1.tar.bz2",
+                #"sha256": computed_checksum,
+                #"basename": "linux-ppc64le/micromamba-10.11.12-linux-ppc64le.tar.bz2",
+                #"version": "10.11.12"
+            #},
+            #{
+                #"attrs": {
+                    #"subdir": "win-64",
+                    #"build_number": 1
+                #},
+                #"download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/win-64/micromamba-10.11.12-1.tar.bz2",
+                #"sha256": computed_checksum,
+                #"basename": "win-64/micromamba-10.11.12-win-64.tar.bz2",
+                #"version": "10.11.12"
+            #},
+            #{
+                #"attrs": {
+                    #"subdir": "osx-64",
+                    #"build_number": 1
+                #},
+                #"download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/osx-64/micromamba-10.11.12-1.tar.bz2",
+                #"sha256": computed_checksum,
+                #"basename": "osx-64/micromamba-10.11.12-osx-64.tar.bz2",
+                #"version": "10.11.12"
+            #},
+            #{
+                #"attrs": {
+                    #"subdir": "osx-arm64",
+                    #"build_number": 1
+                #},
+                #"download_url": "https://anaconda-api/conda-forge/micromamba/10.11.12/osx-arm64/micromamba-10.11.12-1.tar.bz2",
+                #"sha256": computed_checksum,
+                #"basename": "osx-arm64/micromamba-10.11.12-osx-arm64.tar.bz2",
+                #"version": "10.11.12"
+            #}
+        #]
+    #}
+
+    # Use side_effect to simulate different responses for different requests
+    #def side_effect(url, timeout=10):
+        #if "github.com" in url:
+            #return mock_github_response
+        #elif "anaconda.org" in url:
+            #return mock_anaconda_response
+        #else:
+            #raise ValueError(f"Unexpected URL: {url}")
+
+    # Set the side_effect to mock_get
+    #mock_get.side_effect = side_effect
+
+    #mock_get.return_value = mock_response
+
+    # Mock subprocess.check_call to prevent actual command execution
+    #mock_check_call.return_value = None  # Simulate a successful call
+
+    # Mock shutil.copyfile to prevent file copying
+    #mock_copyfile.return_value = None  # Simulate successful copy
+    # Mock shutil.copyfile to simulate copying a valid file
+    #def mock_copyfile_side_effect(*args, **kwargs): #src=None, dst=None, follow_symlinks=True):
+        ## Simulate that the source file exists
+        ## TODO use different versions and subdirs
+        ##if src == 'micromamba-10.11.12-1-linux-64/bin/micromamba':
+            ### Simulate successful copy operation
+            ##assert dst == 'releases/micromamba-linux-64'
+        ##else:
+        #if not args and not kwargs:
+            #raise FileNotFoundError(f"File {src} not found")
+
+    #mock_copyfile.side_effect = mock_copyfile_side_effect
+
+    # Mock existing GitHub tags to simulate the version already being tagged
+    #with patch.object(fetch_release, 'get_all_tags_github', return_value={'2.0.5-0'}):
+        # Run the method with the mocked data
+    fetch_release.get_micromamba('10.11.12', False)
+
+        # Check that the `requests.get` method was called as expected
+        #mock_get.assert_called_once_with("https://api.anaconda.org/release/conda-forge/micromamba/10.11.12")
+
+        # Ensure that subprocess.check_call was called to extract the archive
+        #mock_check_call.assert_called_once_with(
+            #["micromamba", "package", "extract", "micromamba-10.11.12-1-linux-64.tar.bz2", "micromamba-10.11.12-1-linux-64"])
+
+        # Ensure shutil.copyfile is called with the expected paths
+        #mock_copyfile.assert_called_once_with(
+            #'micromamba-10.11.12-1-linux-64/bin/micromamba', 'releases/micromamba-linux-64'
+        #)
+
+
+        # Check that the `requests.get` method was called as expected
+        #mock_get.assert_called_once_with("https://api.anaconda.org/release/conda-forge/micromamba/10.11.12")
+
+        # Ensure that subprocess.check_call was called to extract the archive
+        #mock_check_call.assert_called_once_with(
+            #["micromamba", "package", "extract", "micromamba-10.11.12-1-linux-64.tar.bz2", "micromamba-10.11.12-1-linux-64"])
+
+        # Ensure shutil.copyfile is called with the expected paths
+        #mock_copyfile.assert_called_once_with(
+            #'micromamba-10.11.12-1-linux-64/bin/micromamba', 'releases/micromamba-linux-64'
+        #)
+
+    assert get_output_value("MICROMAMBA_NEW_VERSION") == "true"
+
+
+