Ensure directives get printed in block statements (#4873)

packages/babel-generator/src/generators/base.js

@@ -14,11 +14,14 @@ export function Program(node: Object) {
 export function BlockStatement(node: Object) {
   this.token("{");
   this.printInnerComments(node);
-  if (node.body.length) {
+
+  let hasDirectives = node.directives && node.directives.length;
+
+  if (node.body.length || hasDirectives) {
     this.newline();
 
     this.printSequence(node.directives, node, { indent: true });
-    if (node.directives && node.directives.length) this.newline();
+    if (hasDirectives) this.newline();
 
     this.printSequence(node.body, node, { indent: true });
     this.removeTrailingNewline();

packages/babel-generator/test/index.js

@@ -230,6 +230,20 @@ describe("programmatic generation", function() {
     assert.equal(ast.program.body[0].consequent.type, "BlockStatement");
   });
 
+  it("prints directives in block with empty body", function() {
+    let blockStatement = t.blockStatement(
+      [],
+      [t.directive(t.directiveLiteral("use strict"))]
+    );
+
+    let output = generate.default(blockStatement).code;
+    assert.equal(output, [
+      "{",
+      "  \"use strict\";",
+      "}"
+    ].join("\n"));
+  });
+
   it("flow object indentation", function() {
     let objectStatement = t.objectTypeAnnotation(
       [

packages/babel-plugin-transform-es2015-modules-amd/test/fixtures/amd/get-module-name-option/expected.js

@@ -1 +1,3 @@
-define("my custom module name", [], function () {});
+define("my custom module name", [], function () {
+  "use strict";
+});

packages/babel-plugin-transform-es2015-modules-amd/test/fixtures/amd/imports/expected.js

@@ -1 +1,3 @@
-define(["foo", "foo-bar", "./directory/foo-bar"], function () {});
+define(["foo", "foo-bar", "./directory/foo-bar"], function () {
+  "use strict";
+});

packages/babel-plugin-transform-es2015-modules-umd/test/fixtures/umd/get-module-name-option/expected.js

@@ -10,4 +10,6 @@
     factory();
     global.myCustomModuleName = mod.exports;
   }
-})(this, function () {});
+})(this, function () {
+  "use strict";
+});

packages/babel-plugin-transform-es2015-modules-umd/test/fixtures/umd/imports/expected.js

@@ -10,4 +10,6 @@
     factory(global.foo, global.fooBar, global.fooBar);
     global.actual = mod.exports;
   }
-})(this, function () {});
+})(this, function () {
+  "use strict";
+});

packages/babel-plugin-transform-es2015-modules-umd/test/fixtures/umd/non-default-imports/expected.js

@@ -10,4 +10,6 @@
     factory(global.render);
     global.actual = mod.exports;
   }
-})(this, function (_render) {});
+})(this, function (_render) {
+  "use strict";
+});

packages/babel-plugin-transform-es2015-modules-umd/test/fixtures/umd/override-import-name/expected.js

@@ -10,4 +10,6 @@
     factory(global.baz);
     global.actual = mod.exports;
   }
-})(this, function () {});
+})(this, function () {
+  "use strict";
+});