build: Taskfile improvements (#2032)

- Added individual tasks for black, isort and mypy to make it easier to
  run these directly.
- Change flag variables to be JSON based so that they can be disabled
  with "false", this makes it easier to work with tooling that does not
  distinguish between empty and unset environment variables.
- Add a `venv:run` target to make it easier to run things inside the
  venv, e.g. `task venv:run -- pip install lxml`.
- Change pytest invocation to use the pytest script instead of using
  `python -m pytest` as the latter does some things which are not
  desirable.

2 files changed, 72 insertions, 33 deletions

diff --git a/.github/workflows/validate.yaml b/.github/workflows/validate.yaml
index de545ef5..9f3c9464 100644
--- a/.github/workflows/validate.yaml
+++ b/.github/workflows/validate.yaml
@@ -73,7 +73,7 @@ jobs:
           task \
             TOX_EXTRA_COMMAND="${{ matrix.TOX_EXTRA_COMMAND }}" \
             OS=${{ matrix.os }} \
-            EXTENSIVE=${{ matrix.extensive-tests }} \
+            EXTENSIVE=${{ matrix.extensive-tests || 'false' }} \
             TOX_PYTHON_VERSION=${{ matrix.python-version }} \
             TOXENV_SUFFIX=${{ matrix.TOXENV_SUFFIX }} \
             gha:validate
@@ -85,8 +85,8 @@ jobs:
       fail-fast: false
       matrix:
         include:
-        - task: "gha:flake8"
-          python-version: 3.8
+          - task: "gha:flake8"
+            python-version: 3.8
     steps:
       - uses: actions/checkout@v3
       - name: Set up Python ${{env.DEFAULT_PYTHON}}
diff --git a/Taskfile.yml b/Taskfile.yml
index 60d94c26..985848a6 100644
--- a/Taskfile.yml
+++ b/Taskfile.yml
@@ -1,32 +1,41 @@
+# https://taskfile.dev/usage/
+# https://pkg.go.dev/text/template
+# https://go-task.github.io/slim-sprig/
 version: "3"
 
 vars:
+  TASKFILE_DIR:
+    sh: pwd
   # The path to the virtual environment to use when using a virtual
   # environment.
-  VENV_PATH: '{{default ".venv" (env "VENV_PATH")}}'
+  VENV_PATH: '{{(env "VENV_PATH") | default (osClean (print .TASKFILE_DIR "/.venv"))}}'
   # Non empty string results in tasks using a virtual environment.
-  WITH_VENV: '{{env "WITH_VENV"}}'
+  WITH_VENV: '{{env "WITH_VENV" | default "false"}}'
   # The virtual environemtn specific python interpreter to use.
-  VENV_PYTHON: '{{if (eq OS "windows")}}{{.VENV_PATH}}/Scripts/python.exe{{else}}{{.VENV_PATH}}/bin/python{{end}}'
+  VENV_BINPREFIX: '{{if (mustFromJson .WITH_VENV)}}{{if (eq OS "windows")}}{{.VENV_PATH}}/Scripts/{{else}}{{.VENV_PATH}}/bin/{{end}}{{end}}'
+  VENV_PYTHON: '{{if (eq OS "windows")}}{{.VENV_BINPREFIX}}python.exe{{else}}{{.VENV_BINPREFIX}}python{{end}}'
   # The python interpreter to use.
   PYTHON: python
-  _PYTHON: '{{if .WITH_VENV}}{{.VENV_PYTHON}}{{else}}{{.PYTHON}}{{end}}'
-  # Non empty string results in java being installed as a system dependency.
-  INSTALL_SYSTEM_DEPS_JAVA: ""
-  # Non empty string results in extras being installed with pip.
-  INSTALL_PIP_EXTRAS: ""
-  # Non empty string results in extensive tests being ran and dependencies for
-  # extensive tests being installed.
-  EXTENSIVE: ""
+  _PYTHON: '{{if (mustFromJson .WITH_VENV)}}{{.VENV_PYTHON}}{{else}}{{.PYTHON}}{{end}}'
+  # Truthish values ("true", "1", etc.) results in java being installed as a
+  # system dependency.
+  INSTALL_SYSTEM_DEPS_JAVA: "false"
+  # Truthish values ("true", "1", etc.) results in extras being installed with
+  # pip.
+  INSTALL_PIP_EXTRAS: "false"
+  # Truthish values ("true", "1", etc.) results in extensive tests being ran and
+  # dependencies for extensive tests being installed.
+  EXTENSIVE: "false"
   # The python version for which tox should run, empty string does not restrict
   # python versions.
   TOX_PYTHON_VERSION: ""
-  TEST_HARNESS: '{{if (and .EXTENSIVE (not (eq OS "windows")))}}./with-fuseki.sh{{end}} '
-  # A non empty string results in github specific things being done.
-  WITH_GITHUB_ACTIONS: ""
-  # A non empty string results in coverage being generated for relevant
-  # commands.
-  WITH_COVERAGE: ""
+  TEST_HARNESS: '{{if (and (mustFromJson .EXTENSIVE) (not (eq OS "windows")))}}./with-fuseki.sh{{end}} '
+  # Truthish values ("true", "1", etc.) results in github specific things being
+  # done.
+  WITH_GITHUB_ACTIONS: "false"
+  # Truthish values ("true", "1", etc.) results in coverage being generated for
+  # relevant commands.
+  WITH_COVERAGE: "false"
 
 tasks:
   install:system-deps:
@@ -35,7 +44,7 @@ tasks:
       - echo "OS = {{OS}}"
       - echo "ARCH = {{ARCH}}"
       - |
-        {{if (and .EXTENSIVE (eq OS "linux"))}}
+        {{if (and (mustFromJson .EXTENSIVE) (eq OS "linux"))}}
           if type apt-get >/dev/null 2>&1
           then
             sudo apt-get install -y libdb-dev
@@ -43,19 +52,19 @@ tasks:
           then
             sudo dnf install -y libdb-devel
           fi
-        {{else if (and .EXTENSIVE (eq OS "darwin"))}}
+        {{else if (and (mustFromJson .EXTENSIVE) (eq OS "darwin"))}}
           brew install berkeley-db@4
         {{end}}
 
   install:tox:
     desc: Install tox
     cmds:
-      - "{{._PYTHON}} -m pip install tox {{if .WITH_GITHUB_ACTIONS}}tox-gh-actions{{end}}"
+      - '{{._PYTHON}} -m pip install tox {{if (mustFromJson .WITH_GITHUB_ACTIONS)}}tox-gh-actions{{end}}'
 
   install:pip-deps:
     desc: Install pip dependencies
     cmds:
-      - "{{._PYTHON}} -m pip install --upgrade -r requirements.txt -r requirements.dev.txt -r docs/sphinx-requirements.txt {{if .INSTALL_PIP_EXTRAS}}-r requirements.dev-extras.txt{{end}}"
+      - '{{._PYTHON}} -m pip install --upgrade -r requirements.txt -r requirements.dev.txt -r docs/sphinx-requirements.txt {{if (mustFromJson .INSTALL_PIP_EXTRAS)}}-r requirements.dev-extras.txt{{end}}'
 
   install:flake8:
     desc: Install flake8 dependencies
@@ -82,6 +91,22 @@ tasks:
       - task: _rimraf
         vars: { _PYTHON: "{{.PYTHON}}", RIMRAF_TARGET: "{{.VENV_PATH}}" }
 
+  venv:run:
+    desc: Run a command inside the venv
+    cmds:
+      - cmd: |
+          VIRTUAL_ENV="{{.VENV_PATH}}" PATH="{{.VENV_PATH}}/bin${PATH:+:${PATH}}" {{.CLI_ARGS}}
+
+  run:
+    desc: Run a command. If WITH_VENV is truthish, the command will be run inside the virtual environment.
+    cmds:
+      - cmd: |
+          {{if (mustFromJson .WITH_VENV)}}
+          VIRTUAL_ENV="{{.VENV_PATH}}" PATH="{{.VENV_PATH}}/bin${PATH:+:${PATH}}" {{.CLI_ARGS}}
+          {{else}}
+          {{.CLI_ARGS}}
+          {{end}}
+
   tox:
     desc: Run tox
     cmds:
@@ -95,36 +120,50 @@ tasks:
           -m tox \
           {{.CLI_ARGS}}
     env:
-      TOXENV: '{{if .TOX_PYTHON_VERSION}}py{{mustRegexReplaceAll "^([0-9]+)[.]([0-9]+).*" .TOX_PYTHON_VERSION "${1}${2}"}}{{if .EXTENSIVE}}-extensive{{end}}{{.TOXENV_SUFFIX | default ""}}{{end}}'
+      TOXENV: '{{if .TOX_PYTHON_VERSION}}py{{mustRegexReplaceAll "^([0-9]+)[.]([0-9]+).*" .TOX_PYTHON_VERSION "${1}${2}"}}{{if (mustFromJson .EXTENSIVE)}}-extensive{{end}}{{.TOXENV_SUFFIX | default ""}}{{end}}'
   test:
     desc: Run tests
     cmds:
-      - "{{.TEST_HARNESS}}{{._PYTHON}} -m pytest {{if .WITH_COVERAGE}}--cov --cov-report={{end}} {{.CLI_ARGS}}"
+      - '{{.TEST_HARNESS}}{{.VENV_BINPREFIX}}pytest {{if (mustFromJson .WITH_COVERAGE)}}--cov --cov-report={{end}} {{.CLI_ARGS}}'
 
   flake8:
     desc: Run flake8
     cmds:
       - "{{._PYTHON}} -m flakeheaven lint {{.CLI_ARGS}}"
 
+  black:
+    desc: Run black
+    cmds:
+      - '{{._PYTHON}} -m black {{if (mustFromJson (.CHECK | default "false"))}}--check --diff {{end}}{{.CLI_ARGS | default "."}}'
+  isort:
+    desc: Run isort
+    cmds:
+      - '{{._PYTHON}} -m isort {{if (mustFromJson (.CHECK | default "false"))}}--check --diff {{end}}{{.CLI_ARGS | default "."}}'
+  mypy:
+    desc: Run mypy
+    cmds:
+      - "{{._PYTHON}} -m mypy --show-error-context --show-error-codes"
+
   lint:fix:
     desc: Fix auto-fixable linting errors
     cmds:
-      - "{{._PYTHON}} -m black ."
-      - "{{._PYTHON}} -m isort ."
+      - task: isort
+      - task: black
 
   lint:
     desc: Perform linting
     cmds:
-      - "{{._PYTHON}} -m isort --check --diff ."
-      - "{{._PYTHON}} -m black --check --diff ."
+      - task: isort
+        vars: { CHECK: true }
+      - task: black
+        vars: { CHECK: true }
       - task: flake8
 
-
   validate:static:
     desc: Perform static validation
     cmds:
       - task: lint
-      - "{{._PYTHON}} -m mypy --show-error-context --show-error-codes"
+      - task: mypy
 
   validate:fix:
     desc: Fix auto-fixable validation errors.
@@ -217,7 +256,7 @@ tasks:
       - task: install:system-deps
       - task: install:tox
         vars:
-          WITH_GITHUB_ACTIONS: 1
+          WITH_GITHUB_ACTIONS: true
       - cmd: "{{._PYTHON}} -m pip install coveralls"
       - task: tox
         vars: