fix: Tailwind fails if lektor build run from outside the Lektor pro…

…ject directory (#4)

* fix: type annotation

* test: run tests from outside the Lektor project dir

Two changes to the tests:

1. Run Lektor from cwd rather than the project directory (setting the
   $LEKTOR_PROJECT environment variable so that Lektor can find the
   project).

2. Rather than just checking for "tailwindcss" in the output CSS file,
   check for one of the classes used in the example
   project (e.g. ".flex") to ensure that tailwind actually found the
   source files.

* fix(lektor build): chdir to project dir before running tailwind

lektor_tailwind.py

@@ -22,7 +22,7 @@ def __init__(self, env, id):
         self.watch = False
         self.css_path = config.get("css_path", "static/style.css")
         self.input_css = os.path.join(self.env.root_path, "assets", self.css_path)
-        self.tailwind: threading.Thread | None = None
+        self.tailwind: subprocess.Popen | None = None
 
     def on_setup_env(self, **extra):
         self.init_tailwindcss()
@@ -65,6 +65,7 @@ def compile_css(self, output_path: str):
                 "--minify",
             ],
             check=True,
+            cwd=self.env.root_path,
         )
 
     def on_server_spawn(self, **extra):

tests/test_plugin.py

@@ -17,12 +17,12 @@
 
 
 @pytest.fixture
-def tmp_project(tmp_path):
-    """Chdir into a temporary directory containing a copy of the example
-    test project.
+def tmp_project_path(tmp_path, monkeypatch):
+    """Copy the example test project to a temporary location.
 
     The source files for the lektor_tailwind plugin are copied into the
     the ``packages`` directory of the temporary project.
+
     """
     testdir = Path(__file__).parent
     example = testdir / "example"
@@ -41,20 +41,23 @@ def tmp_project(tmp_path):
     for fn in PACKAGE_FILES:
         shutil.copy(srcdir / fn, packagedir / fn)
 
-    save_cwd = os.getcwd()
-    try:
-        os.chdir(project)
-        yield project
-    finally:
-        os.chdir(save_cwd)
+    monkeypatch.setenv("LEKTOR_PROJECT", os.fspath(project))
+
+    return project
 
 
 @pytest.fixture
-def slow_build(tmp_project):
+def output_css_path(tmp_project_path):
+    """Where to expect the built CSS."""
+    return tmp_project_path / "_build/static/style.css"
+
+
+@pytest.fixture
+def slow_build(tmp_project_path):
     """Delay Lektor server's build_all."""
     build_delay = 0.5
 
-    plugin = tmp_project / "packages/slow_build"
+    plugin = tmp_project_path / "packages/slow_build"
     plugin.mkdir(parents=True)
     plugin.joinpath("setup.py").write_text(dedent("""
         from setuptools import setup
@@ -160,39 +163,42 @@ def _communicate1(self, timeout):
 
 
 @pytest.fixture
-def lektor_server(tmp_project):
+def lektor_server(tmp_project_path):
     with LektorServerFixture() as fixture:
         yield fixture
 
 
-OUTPUT_CSS = Path("_build/static/style.css")
-
-
 @pytest.mark.parametrize("prune", ("--prune", "--no-prune"))
-def test_build_builds_css(tmp_project, prune):
+def test_build_builds_css(tmp_project_path, prune, output_css_path):
     subprocess.run(("lektor", "build", prune), check=True, timeout=30)
-    assert "tailwindcss" in OUTPUT_CSS.read_text()
+    # Check for utility class name rather than just "tailwindcss"
+    # to confirm that tailwind actually found the project source files.
+    assert ".flex" in output_css_path.read_text()
 
 
-def test_server_rebuilds_css_when_template_updated(lektor_server):
+def test_server_rebuilds_css_when_template_updated(
+    lektor_server, tmp_project_path, output_css_path
+):
     lektor_server.wait_for_build()
-    assert "tailwindcss" in OUTPUT_CSS.read_text()
+    assert ".flex" in output_css_path.read_text()
 
-    with open("templates/layout.html", "a") as fp:
+    with open(tmp_project_path / "templates/layout.html", "a") as fp:
         fp.write("""<div class="before:content-['SENTINEL']"></div>\n""")
 
     lektor_server.wait_for_build()
-    assert "SENTINEL" in OUTPUT_CSS.read_text()
+    assert "SENTINEL" in output_css_path.read_text()
 
 
 @pytest.mark.usefixtures("slow_build")  # excercise race condition
-def test_server_rebuilds_css_when_input_css_updated(lektor_server):
+def test_server_rebuilds_css_when_input_css_updated(
+    lektor_server, tmp_project_path, output_css_path
+):
     lektor_server.wait_for_build()
-    assert "tailwindcss" in OUTPUT_CSS.read_text()
+    assert ".flex" in output_css_path.read_text()
 
-    with open("assets/static/style.css", "a") as fp:
+    with open(tmp_project_path / "assets/static/style.css", "a") as fp:
         fp.write(".SENTINEL { color: red }\n")
 
     lektor_server.wait_for_build()
-    assert ".SENTINEL" in OUTPUT_CSS.read_text()
-    assert "tailwindcss" in OUTPUT_CSS.read_text()
+    assert ".SENTINEL" in output_css_path.read_text()
+    assert ".flex" in output_css_path.read_text()