Add pygments to tests session

noxfile.py

@@ -1,5 +1,6 @@
 """Nox sessions."""
 import contextlib
+import shutil
 import sys
 import tempfile
 from pathlib import Path
@@ -140,7 +141,7 @@ def mypy(session: Session) -> None:
 def tests(session: Session) -> None:
     """Run the test suite."""
     install_package(session)
-    install(session, "coverage[toml]", "pytest", "pytest-django")
+    install(session, "coverage[toml]", "pygments", "pytest", "pytest-django")
     try:
         session.run("coverage", "run", "--parallel", "-m", "pytest", *session.posargs)
     finally:
@@ -163,3 +164,33 @@ def typeguard(session: Session) -> None:
     install_package(session)
     install(session, "pytest", "typeguard")
     session.run("pytest", f"--typeguard-packages={package}", *session.posargs)
+
+
+@nox.session(python=python_versions)
+def xdoctest(session: Session) -> None:
+    """Run examples with xdoctest."""
+    args = session.posargs or ["all"]
+    install_package(session)
+    install(session, "xdoctest")
+    session.run("python", "-m", "xdoctest", package, *args)
+
+
+@nox.session(python="3.8")
+def docs(session: Session) -> None:
+    """Build the documentation."""
+    args = session.posargs or ["docs", "docs/_build"]
+
+    if session.interactive and not session.posargs:
+        args.insert(0, "--open-browser")
+
+    builddir = Path("docs", "_build")
+    if builddir.exists():
+        shutil.rmtree(builddir)
+
+    install_package(session)
+    install(session, "sphinx", "sphinx-autobuild")
+
+    if session.interactive:
+        session.run("sphinx-autobuild", *args)
+    else:
+        session.run("sphinx-build", *args)