Add testing

- This brings in the flow test suite that contains a ton of JavaScript parsing edge cases
- This creates snapshot tests using the pretty printer for all of them
- If uncomment `RUN_AST_TESTS` line in `tests/run_specs.js`, it checks ast(pretty_print(x)) == ast(x). Right now, "178 failed, 197 passed, 375 of 377 total". So half of the tests are not passing, most of them are crashes and many of the rest are subtle issues.

package.json

@@ -11,6 +11,19 @@
     "recast": "^0.11.18"
   },
   "devDependencies": {
-    "glob": "^7.1.1"
+    "glob": "^7.1.1",
+    "jest": "^18.0.0",
+    "flow-parser": "^0.37.0"
+  },
+  "scripts": {
+    "test": "jest"
+  },
+  "jest": {
+    "setupFiles": [
+      "<rootDir>/tests_config/run_spec.js"
+    ],
+    "testRegex": [
+      "jsfmt\\.spec\\.js$"
+    ]
   }
 }

tests/abnormal/__snapshots__/jsfmt.spec.js.snap

@@ -0,0 +1,127 @@
+exports[`test break-continue.js 1`] = `
+"function foo() {
+    while(true) { break; }
+}
+
+function bar() {
+    L: do { continue L; } while(false)
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+/src/printer.js:925
+      if (endsWithBrace(doBody))
+          ^
+
+ReferenceError: endsWithBrace is not defined
+    at genericPrintNoParens (/src/printer.js:925:11)
+    at genericPrint (/src/printer.js:166:7)
+    at p (/src/printer.js:111:37)
+    at exports.printComments (/src/comments.js:327:20)
+    at printGenerically (/src/printer.js:111:12)
+    at FastPath.call (/src/fast-path.js:113:16)
+    at genericPrintNoParens (/src/printer.js:963:14)
+    at genericPrint (/src/printer.js:166:7)
+    at p (/src/printer.js:111:37)
+    at exports.printComments (/src/comments.js:327:20)
+"
+`;
+
+exports[`test return.js 1`] = `
+"function bar(x:number) { }
+function foo() {
+    var x = null;
+    if (x == null) return;
+    bar(x);
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+function bar(x: number) {
+  
+}
+function foo() {
+  var x = null;
+  if (x == null)
+    return;
+  bar(x);
+}
+
+"
+`;
+
+exports[`test toplevel_break.js 1`] = `
+"// @flow
+
+break; // error, illegal
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+/node_modules/babylon/lib/index.js:4255
+  throw err;
+  ^
+
+SyntaxError: Unsyntactic break (3:0)
+    at Parser.pp$5.raise (/node_modules/babylon/lib/index.js:4252:13)
+    at Parser.pp$1.parseBreakContinueStatement (/node_modules/babylon/lib/index.js:1843:44)
+    at Parser.pp$1.parseStatement (/node_modules/babylon/lib/index.js:1703:19)
+    at Parser.parseStatement (/node_modules/babylon/lib/index.js:5224:22)
+    at Parser.pp$1.parseBlockBody (/node_modules/babylon/lib/index.js:2139:21)
+    at Parser.pp$1.parseTopLevel (/node_modules/babylon/lib/index.js:1651:8)
+    at Parser.parse (/node_modules/babylon/lib/index.js:1543:17)
+    at Object.parse$1 [as parse] (/node_modules/babylon/lib/index.js:6472:37)
+    at Object.parse (/index.js:34:26)
+    at Object.parse (/node_modules/recast/lib/parser.js:26:34)
+"
+`;
+
+exports[`test toplevel_continue.js 1`] = `
+"// @flow
+
+continue; // error, illegal
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+/node_modules/babylon/lib/index.js:4255
+  throw err;
+  ^
+
+SyntaxError: Unsyntactic continue (3:0)
+    at Parser.pp$5.raise (/node_modules/babylon/lib/index.js:4252:13)
+    at Parser.pp$1.parseBreakContinueStatement (/node_modules/babylon/lib/index.js:1843:44)
+    at Parser.pp$1.parseStatement (/node_modules/babylon/lib/index.js:1703:19)
+    at Parser.parseStatement (/node_modules/babylon/lib/index.js:5224:22)
+    at Parser.pp$1.parseBlockBody (/node_modules/babylon/lib/index.js:2139:21)
+    at Parser.pp$1.parseTopLevel (/node_modules/babylon/lib/index.js:1651:8)
+    at Parser.parse (/node_modules/babylon/lib/index.js:1543:17)
+    at Object.parse$1 [as parse] (/node_modules/babylon/lib/index.js:6472:37)
+    at Object.parse (/index.js:34:26)
+    at Object.parse (/node_modules/recast/lib/parser.js:26:34)
+"
+`;
+
+exports[`test toplevel_return.js 1`] = `
+"// @flow
+
+return; // error, illegal
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+/node_modules/babylon/lib/index.js:4255
+  throw err;
+  ^
+
+SyntaxError: \'return\' outside of function (3:0)
+    at Parser.pp$5.raise (/node_modules/babylon/lib/index.js:4252:13)
+    at Parser.pp$1.parseReturnStatement (/node_modules/babylon/lib/index.js:1939:10)
+    at Parser.pp$1.parseStatement (/node_modules/babylon/lib/index.js:1722:19)
+    at Parser.parseStatement (/node_modules/babylon/lib/index.js:5224:22)
+    at Parser.pp$1.parseBlockBody (/node_modules/babylon/lib/index.js:2139:21)
+    at Parser.pp$1.parseTopLevel (/node_modules/babylon/lib/index.js:1651:8)
+    at Parser.parse (/node_modules/babylon/lib/index.js:1543:17)
+    at Object.parse$1 [as parse] (/node_modules/babylon/lib/index.js:6472:37)
+    at Object.parse (/index.js:34:26)
+    at Object.parse (/node_modules/recast/lib/parser.js:26:34)
+"
+`;
+
+exports[`test toplevel_throw.js 1`] = `
+"// @flow
+
+throw new Error(\'foo\'); // no error
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// @flow
+throw new Error(\"foo\");// no error
+
+"
+`;

tests/abnormal/break-continue.js

@@ -0,0 +1,7 @@
+function foo() {
+    while(true) { break; }
+}
+
+function bar() {
+    L: do { continue L; } while(false)
+}

tests/abnormal/jsfmt.spec.js

@@ -0,0 +1 @@
+run_spec(__dirname);

tests/abnormal/return.js

@@ -0,0 +1,6 @@
+function bar(x:number) { }
+function foo() {
+    var x = null;
+    if (x == null) return;
+    bar(x);
+}

tests/abnormal/toplevel_break.js

@@ -0,0 +1,3 @@
+// @flow
+
+break; // error, illegal

tests/abnormal/toplevel_continue.js

@@ -0,0 +1,3 @@
+// @flow
+
+continue; // error, illegal

tests/abnormal/toplevel_return.js

@@ -0,0 +1,3 @@
+// @flow
+
+return; // error, illegal

tests/abnormal/toplevel_throw.js

@@ -0,0 +1,3 @@
+// @flow
+
+throw new Error('foo'); // no error