Fixes existing testing, adds test coverage of new command

src/documents/tests/test_management.py

@@ -163,7 +163,7 @@ class TestDecryptDocuments(TestCase):
         self.assertEqual(doc.filename, "0000004.pdf")
         self.assertTrue(os.path.isfile(os.path.join(originals_dir, "0000004.pdf")))
         self.assertTrue(os.path.isfile(doc.source_path))
-        self.assertTrue(os.path.isfile(os.path.join(thumb_dir, f"{doc.id:07}.png")))
+        self.assertTrue(os.path.isfile(os.path.join(thumb_dir, f"{doc.id:07}.webp")))
         self.assertTrue(os.path.isfile(doc.thumbnail_path))
 
         with doc.source_file as f:

src/documents/tests/test_management_convert_thumbnail.py

@@ -0,0 +1,168 @@
+import filecmp
+import shutil
+import tempfile
+from io import StringIO
+from pathlib import Path
+from unittest import mock
+
+from django.core.management import call_command
+from django.test import override_settings
+from django.test import TestCase
+from documents.models import Document
+
+
+class TestConvertThumbnails(TestCase):
+    def call_command(self):
+        stdout = StringIO()
+        stderr = StringIO()
+        call_command(
+            "convert_thumbnails",
+            "--no-color",
+            stdout=stdout,
+            stderr=stderr,
+        )
+        return stdout.getvalue(), stderr.getvalue()
+
+    def setUp(self):
+        """
+        Creates a document in the database
+        """
+        super().setUp()
+
+        self.doc = Document.objects.create(
+            pk=1,
+            checksum="A",
+            title="A",
+            content="first document",
+            mime_type="application/pdf",
+        )
+        self.doc.save()
+
+    def pretend_convert_output(self, *args, **kwargs):
+        """
+        Pretends to do the conversion, by copying the input file
+        to the output file
+        """
+        shutil.copy2(
+            Path(kwargs["input_file"].rstrip("[0]")),
+            Path(kwargs["output_file"]),
+        )
+
+    def create_webp_thumbnail_file(self, thumb_dir):
+        """
+        Creates a dummy WebP thumbnail file in the given directory, based on
+        the database Document
+        """
+        thumb_file = Path(thumb_dir) / Path(f"{self.doc.pk:07}.webp")
+        thumb_file.write_text("this is a dummy webp file")
+        return thumb_file
+
+    def create_png_thumbnail_file(self, thumb_dir):
+        """
+        Creates a dummy PNG thumbnail file in the given directory, based on
+        the database Document
+        """
+        thumb_file = Path(thumb_dir) / Path(f"{self.doc.pk:07}.png")
+        thumb_file.write_text("this is a dummy png file")
+        return thumb_file
+
+    @mock.patch("documents.management.commands.convert_thumbnails.run_convert")
+    def test_do_nothing_if_converted(self, run_convert_mock):
+        """
+        GIVEN:
+            - Document exists with default WebP thumbnail path
+        WHEN:
+            - Thumbnail conversion is attempted
+        THEN:
+            - Nothing is converted
+        """
+
+        stdout, _ = self.call_command()
+        run_convert_mock.assert_not_called()
+        self.assertIn("Converting all PNG thumbnails to WebP", stdout)
+
+    @mock.patch("documents.management.commands.convert_thumbnails.run_convert")
+    def test_convert_single_thumbnail(self, run_convert_mock):
+        """
+        GIVEN:
+            - Document exists with PNG thumbnail
+        WHEN:
+            - Thumbnail conversion is attempted
+        THEN:
+            - Single thumbnail is converted
+        """
+
+        run_convert_mock.side_effect = self.pretend_convert_output
+
+        with tempfile.TemporaryDirectory() as thumbnail_dir:
+
+            with override_settings(
+                THUMBNAIL_DIR=thumbnail_dir,
+            ):
+
+                thumb_file = self.create_png_thumbnail_file(thumbnail_dir)
+
+                stdout, _ = self.call_command()
+
+                run_convert_mock.assert_called_once()
+                self.assertIn(f"{thumb_file}", stdout)
+                self.assertIn("Conversion to WebP completed", stdout)
+
+                self.assertFalse(thumb_file.exists())
+                self.assertTrue(thumb_file.with_suffix(".webp").exists())
+
+    @mock.patch("documents.management.commands.convert_thumbnails.run_convert")
+    def test_convert_errors_out(self, run_convert_mock):
+        """
+        GIVEN:
+            - Document exists with PNG thumbnail
+        WHEN:
+            - Thumbnail conversion is attempted, but raises an exception
+        THEN:
+            - Single thumbnail is converted
+        """
+
+        run_convert_mock.side_effect = OSError
+
+        with tempfile.TemporaryDirectory() as thumbnail_dir:
+
+            with override_settings(
+                THUMBNAIL_DIR=thumbnail_dir,
+            ):
+
+                thumb_file = self.create_png_thumbnail_file(thumbnail_dir)
+
+                _, stderr = self.call_command()
+
+                run_convert_mock.assert_called_once()
+                self.assertIn("Error converting thumbnail", stderr)
+                self.assertTrue(thumb_file.exists())
+
+    @mock.patch("documents.management.commands.convert_thumbnails.run_convert")
+    def test_convert_single_thumbnail_no_output(self, run_convert_mock):
+        """
+        GIVEN:
+            - Document exists with PNG thumbnail
+        WHEN:
+            - Thumbnail conversion is attempted, but there is no output WebP
+        THEN:
+            - Single thumbnail is converted
+        """
+
+        with tempfile.TemporaryDirectory() as thumbnail_dir:
+
+            with override_settings(
+                THUMBNAIL_DIR=thumbnail_dir,
+            ):
+
+                thumb_file = self.create_png_thumbnail_file(thumbnail_dir)
+
+                stdout, stderr = self.call_command()
+
+                run_convert_mock.assert_called_once()
+                self.assertIn(f"{thumb_file}", stdout)
+                self.assertNotIn("Conversion to WebP completed", stdout)
+                self.assertIn("Converted thumbnail doesn't exist", stderr)
+
+                self.assertTrue(thumb_file.exists())
+                self.assertFalse(thumb_file.with_suffix(".webp").exists())