Improve LinePaginator to support long lines

1 files changed, 34 insertions, 7 deletions

diff --git a/tests/bot/test_pagination.py b/tests/bot/test_pagination.py
index 0a734b505..f2e2c27ce 100644
--- a/tests/bot/test_pagination.py
+++ b/tests/bot/test_pagination.py
@@ -8,17 +8,44 @@ class LinePaginatorTests(TestCase):
 
     def setUp(self):
         """Create a paginator for the test method."""
-        self.paginator = pagination.LinePaginator(prefix='', suffix='', max_size=30)
-
-    def test_add_line_raises_on_too_long_lines(self):
-        """`add_line` should raise a `RuntimeError` for too long lines."""
-        message = f"Line exceeds maximum page size {self.paginator.max_size - 2}"
-        with self.assertRaises(RuntimeError, msg=message):
-            self.paginator.add_line('x' * self.paginator.max_size)
+        self.paginator = pagination.LinePaginator(prefix='', suffix='', max_size=30,
+                                                  scale_to_size=50)
 
     def test_add_line_works_on_small_lines(self):
         """`add_line` should allow small lines to be added."""
         self.paginator.add_line('x' * (self.paginator.max_size - 3))
+        # Note that the page isn't added to _pages until it's full.
+        self.assertEqual(len(self.paginator._pages), 0)
+
+    def test_add_line_works_on_long_lines(self):
+        """`add_line` should scale long lines up to `scale_to_size`."""
+        self.paginator.add_line('x' * self.paginator.scale_to_size)
+        self.assertEqual(len(self.paginator._pages), 1)
+
+        # Any additional lines should start a new page after `max_size` is exceeded.
+        self.paginator.add_line('x')
+        self.assertEqual(len(self.paginator._pages), 2)
+
+    def test_add_line_continuation(self):
+        """When `scale_to_size` is exceeded, remaining words should be split onto the next page."""
+        self.paginator.add_line('zyz ' * (self.paginator.scale_to_size//4 + 1))
+        self.assertEqual(len(self.paginator._pages), 2)
+
+    def test_add_line_no_continuation(self):
+        """If adding a new line to an existing page would exceed `max_size`, it should start a new
+        page rather than using continuation.
+        """
+        self.paginator.add_line('z' * (self.paginator.max_size - 3))
+        self.paginator.add_line('z')
+        self.assertEqual(len(self.paginator._pages), 1)
+
+    def test_add_line_raises_on_very_long_words(self):
+        """`add_line` should raise if a single long word is added that exceeds `scale_to_size`.
+
+        Note: truncation is also a potential option, but this should not occur from normal usage.
+        """
+        with self.assertRaises(RuntimeError):
+            self.paginator.add_line('x' * (self.paginator.scale_to_size + 1))
 
 
 class ImagePaginatorTests(TestCase):