chainlint.pl: don't require `return|exit|continue` to end with `&&`

In order to check for &&-chain breakage, each time TestParser encounters
a new command, it checks whether the previous command ends with `&&`,
and -- with a couple exceptions -- signals breakage if it does not. The
first exception is that a command may validly end with `||`, which is
commonly employed as `command || return 1` at the very end of a loop
body to terminate the loop early. The second is that piping one
command's output with `|` to another command does not constitute a
&&-chain break (the exit status of the pipe is the exit status of the
final command in the pipe).

However, it turns out that there are a few additional cases found in the
wild in which it is likely safe for `&&` to be missing even when other
commands follow. For instance:

    while {condition-1}
    do
        test {condition-2} || return 1 # or `exit 1` within a subshell
        more-commands
    done

    while {condition-1}
    do
        test {condition-2} || continue
        more-commands
    done

Such cases indicate deliberate thought about failure modes by the test
author, thus flagging them as breaking the &&-chain is not helpful.
Therefore, take these special cases into consideration when checking for
&&-chain breakage.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

6 files changed, 45 insertions, 0 deletions

diff --git a/t/chainlint/chain-break-continue.expect b/t/chainlint/chain-break-continue.expect
new file mode 100644
index 0000000000..47a3457710
--- /dev/null
+++ b/t/chainlint/chain-break-continue.expect
@@ -0,0 +1,12 @@
+git ls-tree --name-only -r refs/notes/many_notes |
+while read path
+do
+	test "$path" = "foobar/non-note.txt" && continue
+	test "$path" = "deadbeef" && continue
+	test "$path" = "de/adbeef" && continue
+
+	if test $(expr length "$path") -ne $hexsz
+	then
+		return 1
+	fi
+done
diff --git a/t/chainlint/chain-break-continue.test b/t/chainlint/chain-break-continue.test
new file mode 100644
index 0000000000..f0af71d8bd
--- /dev/null
+++ b/t/chainlint/chain-break-continue.test
@@ -0,0 +1,13 @@
+git ls-tree --name-only -r refs/notes/many_notes |
+while read path
+do
+# LINT: broken &&-chain okay if explicit "continue"
+	test "$path" = "foobar/non-note.txt" && continue
+	test "$path" = "deadbeef" && continue
+	test "$path" = "de/adbeef" && continue
+
+	if test $(expr length "$path") -ne $hexsz
+	then
+		return 1
+	fi
+done
diff --git a/t/chainlint/chain-break-return-exit.expect b/t/chainlint/chain-break-return-exit.expect
new file mode 100644
index 0000000000..dba292ee89
--- /dev/null
+++ b/t/chainlint/chain-break-return-exit.expect
@@ -0,0 +1,4 @@
+for i in 1 2 3 4 ; do
+	git checkout main -b $i || return $?
+	test_commit $i $i $i tag$i || return $?
+done
diff --git a/t/chainlint/chain-break-return-exit.test b/t/chainlint/chain-break-return-exit.test
new file mode 100644
index 0000000000..e2b059933a
--- /dev/null
+++ b/t/chainlint/chain-break-return-exit.test
@@ -0,0 +1,5 @@
+for i in 1 2 3 4 ; do
+# LINT: broken &&-chain okay if explicit "return $?" signals failure
+	git checkout main -b $i || return $?
+	test_commit $i $i $i tag$i || return $?
+done
diff --git a/t/chainlint/return-loop.expect b/t/chainlint/return-loop.expect
new file mode 100644
index 0000000000..cfc0549bef
--- /dev/null
+++ b/t/chainlint/return-loop.expect
@@ -0,0 +1,5 @@
+while test $i -lt $((num - 5))
+do
+	git notes add -m "notes for commit$i" HEAD~$i || return 1
+	i=$((i + 1))
+done
diff --git a/t/chainlint/return-loop.test b/t/chainlint/return-loop.test
new file mode 100644
index 0000000000..f90b171300
--- /dev/null
+++ b/t/chainlint/return-loop.test
@@ -0,0 +1,6 @@
+while test $i -lt $((num - 5))
+do
+# LINT: "|| return {n}" valid loop escape outside subshell; no "&&" needed
+	git notes add -m "notes for commit$i" HEAD~$i || return 1
+	i=$((i + 1))
+done