test_line_count = 1 done_lines
'
+test_expect_success 'diff does not fetch anything if inexact rename detection is not needed' '
+ test_when_finished "rm -rf server client trace" &&
+
+ test_create_repo server &&
+ echo a >server/a &&
+ printf "b\nb\nb\nb\nb\n" >server/b &&
+ git -C server add a b &&
+ git -C server commit -m x &&
+ mv server/b server/c &&
+ git -C server add c &&
+ git -C server commit -a -m x &&
+
+ test_config -C server uploadpack.allowfilter 1 &&
+ test_config -C server uploadpack.allowanysha1inwant 1 &&
+ git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
+
+ # Ensure no fetches.
+ GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff --raw -M HEAD^ HEAD &&
+ ! test_path_exists trace
+'
+
+test_expect_success 'diff --break-rewrites fetches only if necessary, and batches blobs if it does' '
+ test_when_finished "rm -rf server client trace" &&
+
+ test_create_repo server &&
+ echo a >server/a &&
+ printf "b\nb\nb\nb\nb\n" >server/b &&
+ git -C server add a b &&
+ git -C server commit -m x &&
+ printf "c\nc\nc\nc\nc\n" >server/b &&
+ git -C server commit -a -m x &&
+
+ test_config -C server uploadpack.allowfilter 1 &&
+ test_config -C server uploadpack.allowanysha1inwant 1 &&
+ git clone --bare --filter=blob:limit=0 "file://$(pwd)/server" client &&
+
+ # Ensure no fetches.
+ GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff --raw -M HEAD^ HEAD &&
+ ! test_path_exists trace &&
+
+ # But with --break-rewrites, ensure that there is exactly 1 negotiation
+ # by checking that there is only 1 "done" line sent. ("done" marks the
+ # end of negotiation.)
+ GIT_TRACE_PACKET="$(pwd)/trace" git -C client diff --break-rewrites --raw -M HEAD^ HEAD &&
+ grep "git> done" trace >done_lines &&
+ test_line_count = 1 done_lines
+'
+
test_done