Add bats support

This is motivated by the fact that the popularity of bats is increasing
since the creation of bats-core/bats-core.

The code is a cherry-pick of koalaman/shellcheck/bats branch.

Fix koalaman/shellcheck#417.

src/ShellCheck/AST.hs

@@ -139,6 +139,7 @@ data Token =
     | T_CoProcBody Id Token
     | T_Include Id Token
     | T_SourceCommand Id Token Token
+    | T_BatsTest Id Token Token
     deriving (Show)
 
 data Annotation =
@@ -276,6 +277,7 @@ analyze f g i =
     delve (T_CoProcBody id t) = d1 t $ T_CoProcBody id
     delve (T_Include id script) = d1 script $ T_Include id
     delve (T_SourceCommand id includer t_include) = d2 includer t_include $ T_SourceCommand id
+    delve (T_BatsTest id name t) = d2 name t $ T_BatsTest id
     delve t = return t
 
 getId :: Token -> Id
@@ -380,6 +382,7 @@ getId t = case t of
         T_UnparsedIndex id _ _ -> id
         TC_Empty id _ -> id
         TA_Variable id _ _ -> id
+        T_BatsTest id _ _ -> id
 
 blank :: Monad m => Token -> m ()
 blank = const $ return ()

src/ShellCheck/Analytics.hs

@@ -232,7 +232,9 @@ hasFloatingPoint params = shellType params == Ksh
 isCondition [] = False
 isCondition [_] = False
 isCondition (child:parent:rest) =
-    getId child `elem` map getId (getConditionChildren parent) || isCondition (parent:rest)
+    case child of
+        T_BatsTest {} -> True -- count anything in a @test as conditional
+        _ -> getId child `elem` map getId (getConditionChildren parent) || isCondition (parent:rest)
   where
     getConditionChildren t =
         case t of
@@ -1580,6 +1582,7 @@ prop_subshellAssignmentCheck16 = verifyNotTree subshellAssignmentCheck "(set -e)
 prop_subshellAssignmentCheck17 = verifyNotTree subshellAssignmentCheck "foo=${ { bar=$(baz); } 2>&1; }; echo $foo $bar"
 prop_subshellAssignmentCheck18 = verifyTree subshellAssignmentCheck "( exec {n}>&2; ); echo $n"
 prop_subshellAssignmentCheck19 = verifyNotTree subshellAssignmentCheck "#!/bin/bash\nshopt -s lastpipe; echo a | read -r b; echo \"$b\""
+prop_subshellAssignmentCheck20 = verifyTree subshellAssignmentCheck "@test 'foo' { a=1; }\n@test 'bar' { echo $a; }\n"
 subshellAssignmentCheck params t =
     let flow = variableFlow params
         check = findSubshelled flow [("oops",[])] Map.empty
@@ -1666,6 +1669,7 @@ prop_checkSpacefulness33= verifyTree checkSpacefulness "for file; do echo $file;
 prop_checkSpacefulness34= verifyTree checkSpacefulness "declare foo$n=$1"
 prop_checkSpacefulness35= verifyNotTree checkSpacefulness "echo ${1+\"$1\"}"
 prop_checkSpacefulness36= verifyNotTree checkSpacefulness "arg=$#; echo $arg"
+prop_checkSpacefulness37= verifyNotTree checkSpacefulness "@test 'status' {\n [ $status -eq 0 ]\n}"
 
 checkSpacefulness params t =
     doVariableFlowAnalysis readF writeF (Map.fromList defaults) (variableFlow params)
@@ -1891,6 +1895,7 @@ prop_checkUnused37= verifyNotTree checkUnusedAssignments "fd=2; exec {fd}>&-"
 prop_checkUnused38= verifyTree checkUnusedAssignments "(( a=42 ))"
 prop_checkUnused39= verifyNotTree checkUnusedAssignments "declare -x -f foo"
 prop_checkUnused40= verifyNotTree checkUnusedAssignments "arr=(1 2); num=2; echo \"${arr[@]:num}\""
+prop_checkUnused41= verifyNotTree checkUnusedAssignments "@test 'foo' {\ntrue\n}\n"
 checkUnusedAssignments params t = execWriter (mapM_ warnFor unused)
   where
     flow = variableFlow params

src/ShellCheck/AnalyzerLib.hs

@@ -423,6 +423,7 @@ getVariableFlow params t =
 
     assignFirst T_ForIn {}    = True
     assignFirst T_SelectIn {} = True
+    assignFirst (T_BatsTest {}) = True
     assignFirst _             = False
 
     setRead t =
@@ -440,6 +441,7 @@ leadType params t =
         T_Backticked _ _  -> SubshellScope "`..` expansion"
         T_Backgrounded _ _  -> SubshellScope "backgrounding &"
         T_Subshell _ _  -> SubshellScope "(..) group"
+        T_BatsTest {} -> SubshellScope "@bats test"
         T_CoProcBody _ _  -> SubshellScope "coproc"
         T_Redirecting {}  ->
             if fromMaybe False causesSubshell
@@ -480,6 +482,12 @@ getModifiedVariables t =
             guard $ op `elem` ["=", "*=", "/=", "%=", "+=", "-=", "<<=", ">>=", "&=", "^=", "|="]
             return (t, t, name, DataString $ SourceFrom [rhs])
 
+        T_BatsTest {} -> [
+            (t, t, "lines", DataArray SourceExternal),
+            (t, t, "status", DataString SourceInteger),
+            (t, t, "output", DataString SourceExternal)
+            ]
+
         -- Count [[ -v foo ]] as an "assignment".
         -- This is to prevent [ -v foo ] being unassigned or unused.
         TC_Unary id _ "-v" token -> maybeToList $ do
@@ -699,6 +707,12 @@ getReferencedVariables parents t =
             then concatMap (getIfReference t) [lhs, rhs]
             else []
 
+        T_BatsTest {} -> [ -- pretend @test references vars to avoid warnings
+            (t, t, "lines"),
+            (t, t, "status"),
+            (t, t, "output")
+            ]
+
         t@(T_FdRedirect _ ('{':var) op) -> -- {foo}>&- references and closes foo
             [(t, t, takeWhile (/= '}') var) | isClosingFileOp op]
         x -> getReferencedVariableCommand x

src/ShellCheck/Data.hs

@@ -109,6 +109,7 @@ shellForExecutable name =
     case name of
         "sh"    -> return Sh
         "bash"  -> return Bash
+        "bats"  -> return Bash
         "dash"  -> return Dash
         "ash"   -> return Dash -- There's also a warning for this.
         "ksh"   -> return Ksh

src/ShellCheck/Parser.hs

@@ -2331,6 +2331,17 @@ readBraceGroup = called "brace group" $ do
     id <- endSpan start
     return $ T_BraceGroup id list
 
+prop_readBatsTest = isOk readBatsTest "@test 'can parse' {\n  true\n}"
+readBatsTest = called "bats @test" $ do
+    start <- startSpan
+    try $ string "@test"
+    spacing
+    name <- readNormalWord
+    spacing
+    test <- readBraceGroup
+    id <- endSpan start
+    return $ T_BatsTest id name test
+
 prop_readWhileClause = isOk readWhileClause "while [[ -e foo ]]; do sleep 1; done"
 readWhileClause = called "while loop" $ do
     start <- startSpan
@@ -2590,6 +2601,7 @@ readCompoundCommand = do
         readForClause,
         readSelectClause,
         readCaseClause,
+        readBatsTest,
         readFunctionDefinition
         ]
     spacing
@@ -3037,6 +3049,7 @@ readScriptFile = do
         "ash",
         "dash",
         "bash",
+        "bats",
         "ksh"
         ]
     badShells = [