Migrate a few packages' tests to use Jest Expect (see below)

* Migrate the following packages' tests:
    * babel-helper-annotate-as-pure
    * babel-helper-module-imports
    * babel-helper-transform-fixture-test-runner
    * babel-highlight
    * babel-node
    * babel-plugin-transform-modules-commonjs
    * babel-preset-env-standalone
    * babel-preset-env
    * babel-preset-es2015
    * babel-preset-react
    * babel-standalone
    * babel-template
    * babel-traverse
    * babel-types

packages/babel-plugin-transform-modules-commonjs/test/copied-nodes.js

@@ -1,4 +1,3 @@
-const assert = require("assert");
 const babel = require("@babel/core");
 
 test("Doesn't use the same object for two different nodes in the AST", function() {
@@ -9,26 +8,20 @@ test("Doesn't use the same object for two different nodes in the AST", function(
     plugins: [[require("../"), { loose: true }]],
   }).ast;
 
-  assert.equal(ast.program.body[0].declarations[0].id.type, "Identifier");
-  assert.equal(ast.program.body[2].expression.type, "MemberExpression");
-  assert.equal(ast.program.body[2].expression.object.type, "Identifier");
-  assert.equal(ast.program.body[3].expression.type, "MemberExpression");
-  assert.equal(ast.program.body[3].expression.object.type, "Identifier");
+  expect(ast.program.body[0].declarations[0].id.type).toBe("Identifier");
+  expect(ast.program.body[2].expression.type).toBe("MemberExpression");
+  expect(ast.program.body[2].expression.object.type).toBe("Identifier");
+  expect(ast.program.body[3].expression.type).toBe("MemberExpression");
+  expect(ast.program.body[3].expression.object.type).toBe("Identifier");
 
-  assert.notStrictEqual(
-    ast.program.body[2].expression.object,
+  expect(ast.program.body[2].expression.object).not.toBe(
     ast.program.body[3].expression.object,
-    "Expected different nodes in the AST to not be the same object (one)",
   );
 
-  assert.notStrictEqual(
-    ast.program.body[0].declarations[0].id,
+  expect(ast.program.body[0].declarations[0].id).not.toBe(
     ast.program.body[3].expression.object,
-    "Expected different nodes in the AST to not be the same object (two)",
   );
-  assert.notStrictEqual(
-    ast.program.body[0].declarations[0].id,
+  expect(ast.program.body[0].declarations[0].id).not.toBe(
     ast.program.body[2].expression.object,
-    "Expected different nodes in the AST to not be the same object (three)",
   );
 });

packages/babel-plugin-transform-modules-commonjs/test/esmodule-flag.js

@@ -1,4 +1,3 @@
-const assert = require("assert");
 const babel = require("@babel/core");
 const vm = require("vm");
 
@@ -27,9 +26,5 @@ test("Re-export doesn't overwrite __esModule flag", function() {
   vm.runInNewContext(code, context);
 
   // exports.__esModule shouldn't be overwritten.
-  assert.equal(
-    context.exports.__esModule,
-    true,
-    "Expected exports.__esModule === true",
-  );
+  expect(context.exports.__esModule).toBe(true);
 });