Pin rollup version to fix tree shaking bugs

esinstall/package.json

@@ -53,7 +53,7 @@
     "picomatch": "^2.2.2",
     "rimraf": "^3.0.0",
     "slash": "^3.0.0",
-    "rollup": "^2.34.0",
+    "rollup": "2.37.1",
     "rollup-plugin-polyfill-node": "^0.5.0",
     "validate-npm-package-name": "^3.0.0",
     "vm2": "^3.9.2"

test/esinstall/tree-shake-expression/.gitignore

@@ -0,0 +1 @@
+test-*

test/esinstall/tree-shake-expression/inner-module/main.js

@@ -0,0 +1,8 @@
+
+var wiggle = function wiggle() {
+
+}.bind(this);
+
+export default function() {
+
+}

test/esinstall/tree-shake-expression/inner-module/package.json

@@ -0,0 +1,5 @@
+{
+  "name": "inner-module",
+  "version": "1.0.0",
+  "main": "main.js"
+}

test/esinstall/tree-shake-expression/package.json

@@ -0,0 +1,7 @@
+{
+  "name": "@snowpack/test-tree-shake-expression",
+  "version": "1.0.0",
+  "dependencies": {
+    "inner-module": "file:./inner-module"
+  }
+}

test/esinstall/tree-shake-expression/tree-shake-expression.test.js

@@ -0,0 +1,20 @@
+const fs = require('fs');
+const path = require('path');
+const {runTest} = require('../esinstall-test-utils.js');
+
+const cwd = __dirname;
+
+describe('tree shaking expressions', () => {
+  it('works', async () => {
+    const pkg = 'inner-module';
+    const dest = path.join(cwd, 'test-output');
+    await runTest([pkg], {cwd, dest});
+
+    const output = fs.readFileSync(path.join(dest, `${pkg}.js`), 'utf8');
+
+    expect(output).toEqual(
+      // left hand assignment not removed
+      expect.stringContaining(`var wiggle`)
+    );
+  });
+});

yarn.lock

@@ -8222,6 +8222,9 @@ init-package-json@^1.10.3:
     validate-npm-package-license "^3.0.1"
     validate-npm-package-name "^3.0.0"
 
+"inner-module@file:./test/esinstall/tree-shake-expression/inner-module":
+  version "1.0.0"
+
 inquirer@^6.2.0:
   version "6.5.2"
   resolved "https://registry.yarnpkg.com/inquirer/-/inquirer-6.5.2.tgz#ad50942375d036d327ff528c08bd5fab089928ca"
@@ -12770,6 +12773,13 @@ rollup-pluginutils@^2.8.2:
   dependencies:
     estree-walker "^0.6.1"
 
+[email protected]:
+  version "2.37.1"
+  resolved "https://registry.yarnpkg.com/rollup/-/rollup-2.37.1.tgz#aa7aadffd75c80393f9314f9857e851b0ffd34e7"
+  integrity sha512-V3ojEeyGeSdrMSuhP3diBb06P+qV4gKQeanbDv+Qh/BZbhdZ7kHV0xAt8Yjk4GFshq/WjO7R4c7DFM20AwTFVQ==
+  optionalDependencies:
+    fsevents "~2.1.2"
+
 rollup@^2.23.0, rollup@^2.34.0, rollup@^2.35.1:
   version "2.36.1"
   resolved "https://registry.yarnpkg.com/rollup/-/rollup-2.36.1.tgz#2174f0c25c7b400d57b05628d0e732c7ae8d2178"