Add tests for import assertions

Closes #90. I thought new code was needed to support them, but it turns
out no changes were needed.

babel.config.json

@@ -1,3 +1,6 @@
 {
-  "plugins": ["@babel/plugin-transform-flow-strip-types"]
+  "plugins": [
+    "@babel/plugin-syntax-import-assertions",
+    "@babel/plugin-transform-flow-strip-types"
+  ]
 }

package.json

@@ -10,6 +10,7 @@
   },
   "devDependencies": {
     "@babel/eslint-parser": "7.17.0",
+    "@babel/plugin-syntax-import-assertions": "7.16.7",
     "@babel/plugin-transform-flow-strip-types": "7.16.7",
     "@typescript-eslint/parser": "5.16.0",
     "eslint": "8.12.0",

test/imports.test.js

@@ -1576,6 +1576,7 @@ const flowTests = {
     `import type a, {b} from "a"`,
     `import type {} from "a"`,
     `import type {    } from "a"`,
+    `import json from "./foo.json" assert { type: "json" };`,
 
     // typeof
     `import typeof a from "a"`,
@@ -1672,6 +1673,33 @@ const flowTests = {
       errors: 1,
     },
 
+    // Import assertions.
+    {
+      code: input`
+          |import json from "./foo.json" assert { type: "json" };
+          |import {b, a} from "./bar.json" assert {
+          |  // json
+          |  type: "json",
+          |  a: "b",
+          |} /* bar */ /* end
+          | comment */
+          |;[].forEach()
+      `,
+      output: (actual) => {
+        expect(actual).toMatchInlineSnapshot(`
+          |import {a,b} from "./bar.json" assert {
+          |  // json
+          |  type: "json",
+          |  a: "b",
+          |} /* bar */ 
+          |import json from "./foo.json" assert { type: "json" };/* end
+          | comment */
+          |;[].forEach()
+        `);
+      },
+      errors: 1,
+    },
+
     // https://github.com/graphql/graphql-js/blob/64b194c6c9b9aaa1c139f1b7c3692a6ef851928e/src/execution/execute.js#L10-L69
     {
       code: input`
@@ -1812,6 +1840,7 @@ const typescriptTests = {
     `import type {a} from "a"`,
     `import type {} from "a"`,
     `import type {    } from "a"`,
+    `import json from "./foo.json" assert { type: "json" };`,
 
     // type specifiers.
     `import { type b, type c, a } from "a"`,
@@ -1939,6 +1968,33 @@ const typescriptTests = {
       },
       errors: 1,
     },
+
+    // Import assertions.
+    {
+      code: input`
+          |import json from "./foo.json" assert { type: "json" };
+          |import {b, a} from "./bar.json" assert {
+          |  // json
+          |  type: "json",
+          |  a: "b",
+          |} /* bar */ /* end
+          | comment */
+          |;[].forEach()
+      `,
+      output: (actual) => {
+        expect(actual).toMatchInlineSnapshot(`
+          |import {a,b} from "./bar.json" assert {
+          |  // json
+          |  type: "json",
+          |  a: "b",
+          |} /* bar */ 
+          |import json from "./foo.json" assert { type: "json" };/* end
+          | comment */
+          |;[].forEach()
+        `);
+      },
+      errors: 1,
+    },
   ],
 };