fix(diff): preserve collapsed EOF marker

2026-09-05 09:33:58 +01:00
parent f96f94db8f
commit eafeac5c05
3 changed files with 55 additions and 5 deletions
@@ -114,6 +114,22 @@ describe("computeDiffLines", () => {
    expect(lines.filter((l) => l.kind === "hunk")).toHaveLength(2);
  });

+  it("preserves the EOF marker when a long unterminated trailing run collapses", () => {
+    const trailing = Array.from({ length: 10 }, (_, i) => `t${i}`);
+    const oldText = ["OLD", ...trailing].join("\n");
+    const newText = ["NEW", ...trailing].join("\n");
+
+    expect(texts(computeDiffLines(oldText, newText))).toEqual([
+      ["del", "OLD"],
+      ["add", "NEW"],
+      ["ctx", "t0"],
+      ["ctx", "t1"],
+      ["ctx", "t2"],
+      ["hunk", "⋯ 7 unchanged lines ⋯"],
+      ["eof", "\\ No newline at end of file"],
+    ]);
+  });
+
  it("produces one hunk for the long middle run, none for the short edges", () => {
    // Edge runs (2 lines) fit within their one-sided 3-line context budget;
    // only the interior run (10 lines, budgeted 3+3=6) needs to collapse.