Raise from invalid title page

screenplain/parsers/fountain.py

@@ -256,6 +256,9 @@ def parse_lines(source: list[str]) -> Screenplay:
     Returns a Screenplay object.
 
     """
+    # Strip the leading blank lines.
+    source: list[str] = list(itertools.dropwhile(lambda s: s.strip() == "", source))
+
     source: Generator[str, Any, None] = (_preprocess_line(line) for line in source)
 
     title_page_lines = list(takewhile(lambda line: line != "", source))
@@ -296,7 +299,7 @@ def parse_body(source: Iterator[str]) -> list[SCREENPLAY_TYPES]:
 def parse_title_page(lines: list[str]) -> dict[str, list[str]] | None:
     """Parse the title page.
 
-    Spec: http://fountain.io/syntax#section-titlepage
+    Spec: http://fountain.io/syntax/#title-page
     Returns None if the document does not have a title page section,
     otherwise a dictionary with the data.
 
@@ -310,10 +313,10 @@ def parse_title_page(lines: list[str]) -> dict[str, list[str]] | None:
     it = iter(lines)
     try:
         line = next(it)
+        key_match = title_page_key_re.match(line)
+        if not key_match:
+            return None
         while True:
-            key_match = title_page_key_re.match(line)
-            if not key_match:
-                return None
             key, value = key_match.groups()
             key = key.capitalize()
             if value:
@@ -329,6 +332,10 @@ def parse_title_page(lines: list[str]) -> dict[str, list[str]] | None:
                 else:
                     # Last line has been processed
                     break
+
+            key_match = title_page_key_re.match(line)
+            if not key_match:
+                raise ValueError(f"Invalid title page format on line '{line}'")
     except StopIteration:
         pass
     return result

tests/fountain_test.py

@@ -5,6 +5,8 @@
 from io import StringIO
 from unittest import TestCase
 
+import pytest
+
 from screenplain.parsers import fountain
 from screenplain.richstring import empty_string, italic, plain
 from screenplain.types import (
@@ -618,12 +620,15 @@ def test_empty_value_ignored(self) -> None:
         assert result is not None
         self.assertDictEqual({"Author": ["John August"]}, result)
 
-    def test_unparsable_title_page_returns_none(self) -> None:
+    def test_unparsable_title_page_raises(self) -> None:
         lines = [
             "Title: Inception",
             "    additional line",
         ]
-        self.assertIsNone(fountain.parse_title_page(lines))
+        with pytest.raises(
+            ValueError, match="Invalid title page format on line '    additional line'"
+        ):
+            fountain.parse_title_page(lines)
 
 
 class PageBreakTests(TestCase):

tests/parse_lines/test_title_page.py

@@ -0,0 +1,110 @@
+import pytest
+
+from screenplain.parsers.fountain import parse_lines
+from screenplain.richstring import plain
+from screenplain.types import Action, Screenplay, Slug
+
+TITLE_PAGE_SOURCE = """\
+Title: My Screenplay
+Author: Your Name
+Contact:
+    your.email@example.com
+    (555) 123-4567
+
+FADE IN:
+
+SPACE
+"""
+
+
+def lines(source: str) -> list[str]:
+    return source.split("\n")
+
+
+def test_title_page_keys_and_values() -> None:
+    screenplay = parse_lines(lines(TITLE_PAGE_SOURCE))
+
+    assert isinstance(screenplay, Screenplay)
+    assert {
+        "Title": ["My Screenplay"],
+        "Author": ["Your Name"],
+        "Contact": ["your.email@example.com", "(555) 123-4567"],
+    } == screenplay.title_page
+
+    paras = screenplay.paragraphs
+    assert 2 == len(paras)
+    assert isinstance(paras[0], Action)
+    assert isinstance(paras[1], Action)
+    assert [plain("FADE IN:")] == paras[0].lines
+    assert [plain("SPACE")] == paras[1].lines
+
+
+INVALID_TITLE_PAGE_SOURCE = """\
+Title: My Screenplay
+Author: Your Name
+Contact:
+    your.email@example.com
+    (555) 123-4567
+@ANDREW
+Hi there
+"""
+
+
+def test_invalid_title_page_raises() -> None:
+    with pytest.raises(ValueError, match="Invalid title page format on line '@ANDREW'"):
+        _screenplay = parse_lines(lines(INVALID_TITLE_PAGE_SOURCE))
+
+
+NO_TITLE_TEST = """\
+INT. SOMEWHERE - DAY
+
+Some action.
+"""
+
+
+def test_no_title_page() -> None:
+    screenplay = parse_lines(lines(NO_TITLE_TEST))
+
+    assert {} == screenplay.title_page
+    paras = screenplay.paragraphs
+    assert 2 == len(paras)
+    assert isinstance(paras[0], Slug)
+    assert isinstance(paras[1], Action)
+
+
+def test_empty_source() -> None:
+    screenplay = parse_lines([])
+
+    assert {} == screenplay.title_page
+    assert [] == screenplay.paragraphs
+
+
+EMPTY_START_TEST = """
+
+Title: My Screenplay
+Author: Your Name
+Contact:
+    your.email@example.com
+    (555) 123-4567
+
+FADE IN:
+
+SPACE"""
+
+
+def test_leading_empty_lines() -> None:
+    screenplay = parse_lines(lines(EMPTY_START_TEST))
+
+    assert isinstance(screenplay, Screenplay)
+    assert {
+        "Title": ["My Screenplay"],
+        "Author": ["Your Name"],
+        "Contact": ["your.email@example.com", "(555) 123-4567"],
+    } == screenplay.title_page
+
+    paras = screenplay.paragraphs
+    assert 2 == len(paras)
+    assert isinstance(paras[0], Action)
+    assert isinstance(paras[1], Action)
+    assert [plain("FADE IN:")] == paras[0].lines
+    assert [plain("SPACE")] == paras[1].lines