docs: cite the kenji-nx AppPath line

MainActivity.kt:294 is blank at 53d32a76. The AppPath assignment the data root rests on is line 295.

emulators/kenji-nx.yml

@@ -22,7 +22,7 @@ mode: standalone
 data_root:
   android:
     path: "Android/data/org.kenjinx.android/files"
-    source_ref: "src/KenjinxAndroid/app/src/main/java/org/kenjinx/android/MainActivity.kt:279,294, src/LibKenjinx/LibKenjinx.cs:59-68, src/Ryujinx.Common/Configuration/AppDataManager.cs:84-95"
+    source_ref: "src/KenjinxAndroid/app/src/main/java/org/kenjinx/android/MainActivity.kt:279,295, src/LibKenjinx/LibKenjinx.cs:59-68, src/Ryujinx.Common/Configuration/AppDataManager.cs:84-95"
   windows:
     path: "%APPDATA%/Ryujinx"
     source_ref: "src/Ryujinx.Common/Configuration/AppDataManager.cs:11-12, 52-82"

tests/test_cited_lines.py

@@ -0,0 +1,54 @@
+"""Citations corrected by hand land on the code they describe, at the pin.
+
+Each row is a citation that once named a blank line one or two lines above
+its target. Read from the upstream cache, offline, and skipped where the cache
+does not hold the file.
+"""
+
+from __future__ import annotations
+
+import re
+import sys
+import unittest
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(ROOT / "scripts"))
+
+import upstream  # noqa: E402
+from safeparse import yaml_load  # noqa: E402
+
+CACHE = ROOT / ".cache" / "upstream"
+
+# (profile, cited path, cited line, text the line holds)
+CITATIONS = [
+    (
+        "kenji-nx",
+        "src/KenjinxAndroid/app/src/main/java/org/kenjinx/android/MainActivity.kt",
+        295,
+        "AppPath = this.getExternalFilesDir(null)!!.absolutePath",
+    ),
+]
+
+
+class CitedLinesHoldTheirCode(unittest.TestCase):
+    def test_each_citation_is_in_the_profile_and_on_its_code(self):
+        for profile, path, line, text in CITATIONS:
+            with self.subTest(profile=profile, path=path):
+                raw = (ROOT / "emulators" / f"{profile}.yml").read_text(encoding="utf-8")
+                cited = re.escape(path.rsplit("/", 1)[-1]) + rf":(?:[\d,-]+,)?{line}\b"
+                self.assertRegex(raw, cited)
+                document = yaml_load(raw)
+                repo = upstream.parse_repo(str(document["source"]))
+                try:
+                    lines = upstream.fetch_file(
+                        repo, str(document["source_commit"]), path, str(CACHE), True
+                    )
+                except upstream.NotCachedError:
+                    self.skipTest(f"{path} is not in the upstream cache")
+                self.assertIsNotNone(lines)
+                self.assertIn(text, lines[line - 1])
+
+
+if __name__ == "__main__":
+    unittest.main()