Also infer parser when using --list-different (prettier#1997)

* Also infer parser when using `--list-different`

* Add integration tests for parser inference

bin/prettier.js

@@ -299,7 +299,12 @@ if (stdin) {
     }
 
     if (argv["list-different"]) {
-      if (!prettier.check(input, options)) {
+      if (
+        !prettier.check(
+          input,
+          Object.assign({}, options, { filepath: filename })
+        )
+      ) {
         if (!write) {
           console.log(filename);
         }

tests_integration/__tests__/__snapshots__/with-parser-inference.js.snap

@@ -0,0 +1,13 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`infers postcss parser 1`] = `
+"/* JavaScript */
+\\"use strict\\";
+/* Stylesheet */
+* {
+  outline: none;
+}
+"
+`;
+
+exports[`infers postcss parser with --list-different 1`] = `""`;

tests_integration/__tests__/with-parser-inference.js

@@ -0,0 +1,18 @@
+"use strict";
+
+const runPrettier = require("../runPrettier");
+
+test("infers postcss parser", () => {
+  const result = runPrettier("cli/with-parser-inference", ["*"]);
+
+  expect(result.stdout).toMatchSnapshot();
+});
+
+test("infers postcss parser with --list-different", () => {
+  const result = runPrettier("cli/with-parser-inference", [
+    "--list-different",
+    "*"
+  ]);
+
+  expect(result.stdout).toMatchSnapshot();
+});

tests_integration/cli/with-parser-inference/javascript.js

@@ -0,0 +1,2 @@
+/* JavaScript */
+"use strict";

tests_integration/cli/with-parser-inference/stylesheet.css

@@ -0,0 +1,4 @@
+/* Stylesheet */
+* {
+  outline: none;
+}