t/chainlint: add chainlint "loop" and "conditional" test cases

The --chain-lint option uses heuristics and knowledge of shell syntax to
detect broken &&-chains in subshells by pure textual inspection. The
heuristics handle a range of stylistic variations in existing tests
(evolved over the years), however, they are still best-guesses. As such,
it is possible for future changes to accidentally break assumptions upon
which the heuristics are based. Protect against this possibility by
adding tests which check the linter itself for correctness.

In addition to protecting against regressions, these tests help document
(for humans) expected behavior, which is important since the linter's
implementation language ('sed') does not necessarily lend itself to easy
comprehension.

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

t/chainlint/case.expect

@@ -0,0 +1,19 @@
+(
+	case "$x" in
+	x) foo ;;
+	*) bar ;;
+	esac &&
+	foobar
+>) &&
+(
+	case "$x" in
+	x) foo ;;
+	*) bar ;;
+?!AMP?!	esac
+	foobar
+>) &&
+(
+	case "$x" in 1) true;; esac &&
+?!AMP?!	case "$y" in 2) false;; esac
+	foobar
+>)

t/chainlint/case.test

@@ -0,0 +1,23 @@
+(
+# LINT: "...)" arms in 'case' not misinterpreted as subshell-closing ")"
+	case "$x" in
+	x) foo ;;
+	*) bar ;;
+	esac &&
+	foobar
+) &&
+(
+# LINT: missing "&&" on 'esac'
+	case "$x" in
+	x) foo ;;
+	*) bar ;;
+	esac
+	foobar
+) &&
+(
+# LINT: "...)" arm in one-liner 'case' not misinterpreted as closing ")"
+	case "$x" in 1) true;; esac &&
+# LINT: same but missing "&&"
+	case "$y" in 2) false;; esac
+	foobar
+)

t/chainlint/exit-loop.expect

@@ -0,0 +1,24 @@
+(
+	for i in a b c
+	do
+		foo || exit 1
+		bar &&
+		baz
+	done
+>) &&
+(
+	while true
+	do
+		foo || exit 1
+		bar &&
+		baz
+	done
+>) &&
+(
+	i=0 &&
+	while test $i -lt 10
+	do
+		echo $i || exit
+		i=$(($i + 1))
+	done
+>)

t/chainlint/exit-loop.test

@@ -0,0 +1,27 @@
+(
+	for i in a b c
+	do
+# LINT: "|| exit {n}" valid for-loop escape in subshell; no "&&" needed
+		foo || exit 1
+		bar &&
+		baz
+	done
+) &&
+(
+	while true
+	do
+# LINT: "|| exit {n}" valid while-loop escape in subshell; no "&&" needed
+		foo || exit 1
+		bar &&
+		baz
+	done
+) &&
+(
+	i=0 &&
+	while test $i -lt 10
+	do
+# LINT: "|| exit" (sans exit code) valid escape in subshell; no "&&" needed
+		echo $i || exit
+		i=$(($i + 1))
+	done
+)

t/chainlint/for-loop.expect

@@ -0,0 +1,11 @@
+(
+	for i in a b c
+	do
+?!AMP?!		echo $i
+		cat
+?!AMP?!	done
+	for i in a b c; do
+		echo $i &&
+		cat $i
+	done
+>)

t/chainlint/for-loop.test

@@ -0,0 +1,19 @@
+(
+# LINT: 'for', 'do', 'done' do not need "&&"
+	for i in a b c
+	do
+# LINT: missing "&&" on 'echo'
+		echo $i
+# LINT: last statement of while does not need "&&"
+		cat <<-\EOF
+		bar
+		EOF
+# LINT: missing "&&" on 'done'
+	done
+
+# LINT: 'do' on same line as 'for'
+	for i in a b c; do
+		echo $i &&
+		cat $i
+	done
+)

t/chainlint/if-then-else.expect

@@ -0,0 +1,19 @@
+(
+	if test -n ""
+	then
+?!AMP?!		echo very
+		echo empty
+	elif test -z ""
+		echo foo
+	else
+		echo foo &&
+		cat
+?!AMP?!	fi
+	echo poodle
+>) &&
+(
+	if test -n ""; then
+		echo very &&
+?!AMP?!		echo empty
+	if
+>)

t/chainlint/if-then-else.test

@@ -0,0 +1,28 @@
+(
+# LINT: 'if', 'then', 'elif', 'else', 'fi' do not need "&&"
+	if test -n ""
+	then
+# LINT: missing "&&" on 'echo'
+		echo very
+# LINT: last statement before 'elif' does not need "&&"
+		echo empty
+	elif test -z ""
+# LINT: last statement before 'else' does not need "&&"
+		echo foo
+	else
+		echo foo &&
+# LINT: last statement before 'fi' does not need "&&"
+		cat <<-\EOF
+		bar
+		EOF
+# LINT: missing "&&" on 'fi'
+	fi
+	echo poodle
+) &&
+(
+# LINT: 'then' on same line as 'if'
+	if test -n ""; then
+		echo very &&
+		echo empty
+	if
+)

t/chainlint/while-loop.expect

@@ -0,0 +1,11 @@
+(
+	while true
+	do
+?!AMP?!		echo foo
+		cat
+?!AMP?!	done
+	while true; do
+		echo foo &&
+		cat bar
+	done
+>)

t/chainlint/while-loop.test

@@ -0,0 +1,19 @@
+(
+# LINT: 'while, 'do', 'done' do not need "&&"
+	while true
+	do
+# LINT: missing "&&" on 'echo'
+		echo foo
+# LINT: last statement of while does not need "&&"
+		cat <<-\EOF
+		bar
+		EOF
+# LINT: missing "&&" on 'done'
+	done
+
+# LINT: 'do' on same line as 'while'
+	while true; do
+		echo foo &&
+		cat bar
+	done
+)