diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 0179f42..6c336f2 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -6,28 +6,37 @@ jobs:
   build-linux:
     runs-on: ubuntu-latest
     timeout-minutes: 5
-
+    strategy:
+      matrix:
+        env: [current, next]
     steps:
     - uses: actions/checkout@v2
-    - name: Set up Python
-      uses: actions/setup-python@v2
-      with:
-        python-version: 3.6
-    - name: Install dependencies
+    - name: update conda env
+      shell: bash
       run: |
-        # $CONDA is an environment variable pointing to the root of the miniconda directory
-        # note that most requirements are dependencies of iris so don't need to explicitly include
-        $CONDA/bin/conda install -c conda-forge python=3.6 iris=2.2.0 numpy=1.15 cartopy=0.17.0 cftime=1.0.0b1 mo_pack imagehash
-    - name: Lint with flake8
+        source '/usr/share/miniconda/etc/profile.d/conda.sh'
+        conda install -c conda-forge mamba
+        mamba env update -q --file envs/default-${{ matrix.env }}.yml --name default-${{ matrix.env }}
+    - name: conda info
       run: |
-        $CONDA/bin/conda install flake8
-        # stop the build if there are Python syntax errors or undefined names
-        # TODO: Add/sub more codes below
-        $CONDA/bin/flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
-        # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
-        $CONDA/bin/flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
-    - name: Test with pytest
+        source '/usr/share/miniconda/etc/profile.d/conda.sh'
+        conda activate default-${{ matrix.env }}
+        conda info
+        conda list
+    - name: pytest
       run: |
-        conda install pytest
+        source '/usr/share/miniconda/etc/profile.d/conda.sh'
+        conda activate default-${{ matrix.env }}
         cd lib
-        $CONDA/bin/pytest
+        pytest -p no:warnings -v
+    - name: flake8
+      run: |
+        source '/usr/share/miniconda/etc/profile.d/conda.sh'
+        conda activate default-${{ matrix.env }}
+        flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics --exit-zero --max-complexity=10 --max-line-length=127
+    - name: Sphinx
+      run: |
+        source '/usr/share/miniconda/etc/profile.d/conda.sh'
+        conda activate default-${{ matrix.env }}
+        cd docsrc
+        make github
diff --git a/envs/default-current.yml b/envs/default-current.yml
new file mode 100644
index 0000000..fa2704a
--- /dev/null
+++ b/envs/default-current.yml
@@ -0,0 +1,17 @@
+# Use this file to create a conda environment using:
+# conda env create --file envs/default-current.yml
+
+name: default-current
+channels:
+  - conda-forge
+dependencies:
+  - python=3.6
+  - iris=2.2
+  - numpy=1.15
+  - cartopy=0.17.0
+  - cftime=1.0.0b1
+  - mo_pack
+  - imagehash
+  - pytest
+  - flake8
+  - sphinx=3.4.3
diff --git a/envs/default-next.yml b/envs/default-next.yml
new file mode 100644
index 0000000..ef5e01b
--- /dev/null
+++ b/envs/default-next.yml
@@ -0,0 +1,17 @@
+# Use this file to create a conda environment using:
+# conda env create --file envs/default-next.yml
+
+name: default-next
+channels:
+  - conda-forge
+dependencies:
+  - python=3.7
+  - iris=2.4
+  - numpy=1.15
+  - cartopy=0.17.0
+  - cftime=1.0.0b1
+  - mo_pack
+  - imagehash
+  - pytest
+  - flake8
+  - sphinx=3.4.3