t/chainlint: add chainlint "basic" 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/arithmetic-expansion.expect

@@ -0,0 +1,9 @@
+(
+	foo &&
+	bar=$((42 + 1)) &&
+	baz
+>) &&
+(
+?!AMP?!	bar=$((42 + 1))
+	baz
+>)

t/chainlint/arithmetic-expansion.test

@@ -0,0 +1,11 @@
+(
+	foo &&
+# LINT: closing ")" of $((...)) not misinterpreted as subshell-closing ")"
+	bar=$((42 + 1)) &&
+	baz
+) &&
+(
+# LINT: missing "&&" on $((...))
+	bar=$((42 + 1))
+	baz
+)

t/chainlint/broken-chain.expect

@@ -0,0 +1,6 @@
+(
+	foo &&
+?!AMP?!	bar
+	baz &&
+	wop
+>)

t/chainlint/broken-chain.test

@@ -0,0 +1,8 @@
+(
+	foo &&
+# LINT: missing "&&" from 'bar'
+	bar
+	baz &&
+# LINT: final statement before closing ")" legitimately lacks "&&"
+	wop
+)

t/chainlint/close-subshell.expect

@@ -0,0 +1,25 @@
+(
+	foo
+>) &&
+(
+	bar
+>) >out &&
+(
+	baz
+>) 2>err &&
+(
+	boo
+>) <input &&
+(
+	bip
+>) | wuzzle &&
+(
+	bop
+>) | fazz 	fozz &&
+(
+	bup
+>) |
+fuzzle &&
+(
+	yop
+>)

t/chainlint/close-subshell.test

@@ -0,0 +1,27 @@
+# LINT: closing ")" with various decorations ("&&", ">", "|", etc.)
+(
+	foo
+) &&
+(
+	bar
+) >out &&
+(
+	baz
+) 2>err &&
+(
+	boo
+) <input &&
+(
+	bip
+) | wuzzle &&
+(
+	bop
+) | fazz \
+	fozz &&
+(
+	bup
+) |
+fuzzle &&
+(
+	yop
+)

t/chainlint/command-substitution.expect

@@ -0,0 +1,9 @@
+(
+	foo &&
+	bar=$(gobble) &&
+	baz
+>) &&
+(
+?!AMP?!	bar=$(gobble blocks)
+	baz
+>)

t/chainlint/command-substitution.test

@@ -0,0 +1,11 @@
+(
+	foo &&
+# LINT: closing ")" of $(...) not misinterpreted as subshell-closing ")"
+	bar=$(gobble) &&
+	baz
+) &&
+(
+# LINT: missing "&&" on $(...)
+	bar=$(gobble blocks)
+	baz
+)

t/chainlint/exit-subshell.expect

@@ -0,0 +1,5 @@
+(
+	foo || exit 1
+	bar &&
+	baz
+>)

t/chainlint/exit-subshell.test

@@ -0,0 +1,6 @@
+(
+# LINT: "|| exit {n}" valid subshell escape without hurting &&-chain
+	foo || exit 1
+	bar &&
+	baz
+)

t/chainlint/multi-line-string.expect

@@ -0,0 +1,9 @@
+(
+	x=line 1		line 2		line 3" &&
+?!AMP?!	y=line 1		line2'
+	foobar
+>) &&
+(
+	echo "there's nothing to see here" &&
+	exit
+>)

t/chainlint/multi-line-string.test

@@ -0,0 +1,15 @@
+(
+	x="line 1
+		line 2
+		line 3" &&
+# LINT: missing "&&" on assignment
+	y='line 1
+		line2'
+	foobar
+) &&
+(
+# LINT: apostrophe (in a contraction) within string not misinterpreted as
+# LINT: starting multi-line single-quoted string
+	echo "there's nothing to see here" &&
+	exit
+)

t/chainlint/pipe.expect

@@ -0,0 +1,8 @@
+(
+	foo |
+	bar |
+	baz &&
+	fish |
+?!AMP?!	cow
+	sunder
+>)

t/chainlint/pipe.test

@@ -0,0 +1,12 @@
+(
+# LINT: no "&&" needed on line ending with "|"
+	foo |
+	bar |
+	baz &&
+
+# LINT: final line of pipe sequence ('cow') lacking "&&"
+	fish |
+	cow
+
+	sunder
+)

t/chainlint/semicolon.expect

@@ -0,0 +1,20 @@
+(
+?!AMP?!?!SEMI?!	cat foo ; echo bar
+?!SEMI?!	cat foo ; echo bar
+>) &&
+(
+?!SEMI?!	cat foo ; echo bar &&
+?!SEMI?!	cat foo ; echo bar
+>) &&
+(
+	echo "foo; bar" &&
+?!SEMI?!	cat foo; echo bar
+>) &&
+(
+?!SEMI?!	foo;
+>) &&
+(
+cd foo &&
+	for i in a b c; do
+?!SEMI?!		echo;
+>	done)

t/chainlint/semicolon.test

@@ -0,0 +1,25 @@
+(
+# LINT: missing internal "&&" and ending "&&"
+	cat foo ; echo bar
+# LINT: final statement before ")" only missing internal "&&"
+	cat foo ; echo bar
+) &&
+(
+# LINT: missing internal "&&"
+	cat foo ; echo bar &&
+	cat foo ; echo bar
+) &&
+(
+# LINT: not fooled by semicolon in string
+	echo "foo; bar" &&
+	cat foo; echo bar
+) &&
+(
+# LINT: unnecessary terminating semicolon
+	foo;
+) &&
+(cd foo &&
+	for i in a b c; do
+# LINT: unnecessary terminating semicolon
+		echo;
+	done)