Expand function definition to support subshell and tests (#83)

Fixes https://github.com/tree-sitter/tree-sitter-bash/issues/60

corpus/statements.txt

@@ -365,6 +365,12 @@ do_something() {
   echo ok
 }
 
+run_subshell_command() (
+  true
+)
+
+run_test_command() [[ -e foo ]]
+
 function do_something_else() {
   a | xargs -I{} find xml/{} -type f
 }
@@ -379,6 +385,12 @@ function do_yet_another_thing {
   (function_definition
     (word)
     (compound_statement (command (command_name (word)) (word))))
+  (function_definition
+      (word)
+      (subshell (command (command_name (word)))))
+  (function_definition
+      (word)
+      (test_command (unary_expression (test_operator) (word))))
   (function_definition
     (word)
     (compound_statement

grammar.js

@@ -213,7 +213,13 @@ module.exports = grammar({
           '(', ')'
         )
       ),
-      field('body', $.compound_statement)
+      field(
+        'body',
+        choice(
+          $.compound_statement,
+          $.subshell,
+          $.test_command)
+      )
     ),
 
     compound_statement: $ => seq(

src/grammar.json

@@ -839,8 +839,21 @@
           "type": "FIELD",
           "name": "body",
           "content": {
-            "type": "SYMBOL",
-            "name": "compound_statement"
+            "type": "CHOICE",
+            "members": [
+              {
+                "type": "SYMBOL",
+                "name": "compound_statement"
+              },
+              {
+                "type": "SYMBOL",
+                "name": "subshell"
+              },
+              {
+                "type": "SYMBOL",
+                "name": "test_command"
+              }
+            ]
           }
         }
       ]

src/node-types.json

@@ -714,6 +714,14 @@
           {
             "type": "compound_statement",
             "named": true
+          },
+          {
+            "type": "subshell",
+            "named": true
+          },
+          {
+            "type": "test_command",
+            "named": true
           }
         ]
       },