From a19a77f105321de6505b166604ecf80edc7a9ce6 Mon Sep 17 00:00:00 2001
From: Sven van Heugten <sven@memcmp.org>
Date: Thu, 5 Mar 2026 20:42:13 +0100
Subject: [PATCH] Add a test where all pairs in a hunk become context

---
 test/mechanicaldiff.bats | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/test/mechanicaldiff.bats b/test/mechanicaldiff.bats
index 13a01b0..a0a1e75 100755
--- a/test/mechanicaldiff.bats
+++ b/test/mechanicaldiff.bats
@@ -156,3 +156,22 @@ setup() {
   output_normalized="$(printf '%s\n' "$output" | sed -e '/^index /d')"
   assert_equal "$expected" "$output_normalized"
 }
+
+@test "drops hunk when all pairs become context" {
+  cat >"$BATS_TEST_TMPDIR/old" <<-'EOF'
+	foo
+	bar
+	baz
+	EOF
+  sed \
+    -e 's/foo/foo_changed/' \
+    -e 's/bar/bar_changed/' \
+    "$BATS_TEST_TMPDIR/old" >"$BATS_TEST_TMPDIR/new"
+
+  git diff --no-index "$BATS_TEST_TMPDIR/old" "$BATS_TEST_TMPDIR/new" \
+    >"$BATS_TEST_TMPDIR/diff_full" || true
+
+  run mechanicaldiff.py qux quux <"$BATS_TEST_TMPDIR/diff_full"
+  assert_failure
+  assert_output ""
+}