template.expression should not parse string without interpolation as …

…statement (#196)

If a template doesn't have any interpolation parameters (e.g., expression`function() {}`),
it should be also surrounded by () to force parsing as expression.

src/__tests__/template-test.js

@@ -111,6 +111,18 @@ while (i < 10) {
     .toEqual(expected);
   });
 
+  it('correctly parses expressions without any interpolation', () => {
+    const expected = 'function() {}';
+
+    expect(
+      jscodeshift(
+        expression`function() {}`
+      )
+      .toSource()
+    )
+    .toEqual(expected);
+  });
+
   describe('explode arrays', () => {
 
     it('explodes arrays in function definitions', () => {

src/template.js

@@ -132,11 +132,9 @@ module.exports = function withParser(parser) {
   function expression(template/*, ...nodes*/) {
     // wrap code in `(...)` to force evaluation as expression
     template = Array.from(template);
-    if (template.length > 1) {
+    if (template.length > 0) {
       template[0] = '(' + template[0];
       template[template.length - 1] += ')';
-    } else if (template.length === 0) {
-      template[0] = '(' + template[0] + ')';
     }
 
     return statement.apply(