Check full JS output for hello world

tests/code_size/hello_world_wasm.js

@@ -0,0 +1,27 @@
+var d = Module;
+
+var e = new TextDecoder("utf8");
+
+function f(a) {
+    if (!a) return "";
+    for (var b = a + NaN, c = a; !(c >= b) && g[c]; ) ++c;
+    return e.decode(g.subarray(a, c));
+}
+
+var g, h, k;
+
+WebAssembly.instantiate(d.wasm, {
+    a: {
+        a: function(a) {
+            console.log(f(a));
+        }
+    }
+}).then((function(a) {
+    a = a.instance.exports;
+    k = a.e;
+    h = a.b;
+    var b = h.buffer;
+    g = new Uint8Array(b);
+    a.d();
+    k();
+}));

tests/code_size/hello_world_wasm2js.js

@@ -0,0 +1,79 @@
+var b = Module;
+
+var c = new TextDecoder("utf8");
+
+function e(a) {
+    if (!a) return "";
+    for (var m = a + NaN, d = a; !(d >= m) && f[d]; ) ++d;
+    return c.decode(f.subarray(a, d));
+}
+
+var f, g;
+
+g = new function(a) {
+    this.buffer = new ArrayBuffer(65536 * a.initial);
+}({
+    initial: 256,
+    maximum: 256
+});
+
+var h = g.buffer;
+
+f = new Uint8Array(h);
+
+var k = {
+    a: function(a) {
+        console.log(e(a));
+    },
+    memory: g
+}, l, n = (new function() {
+    this.exports = function instantiate(t) {
+        function r(u) {
+            u.set = function(v, w) {
+                this[v] = w;
+            };
+            u.get = function(v) {
+                return this[v];
+            };
+            return u;
+        }
+        function s(x) {
+            var a = Math.imul;
+            var b = Math.fround;
+            var c = Math.abs;
+            var d = Math.clz32;
+            var e = Math.min;
+            var f = Math.max;
+            var g = Math.floor;
+            var h = Math.ceil;
+            var i = Math.trunc;
+            var j = Math.sqrt;
+            var k = x.abort;
+            var l = NaN;
+            var m = Infinity;
+            var n = x.a;
+            function q(a, b) {
+                a = a | 0;
+                b = b | 0;
+                n(1024);
+                return 0;
+            }
+            function p() {}
+            var o = r([]);
+            return {
+                b: o,
+                c: p,
+                d: q
+            };
+        }
+        return s(t);
+    }(k);
+}).exports;
+
+l = n.d;
+
+f.set(new Uint8Array(b.mem), 1024);
+
+n.c();
+
+l();

tests/test_other.py

@@ -8189,16 +8189,16 @@ def test(args, closure, opt):
   @no_windows("Code size is slightly different on Windows")
   @no_mac("Code size is slightly different on Mac")
   @parameterized({
-    'hello_world_wasm': ('hello_world', False),
-    'hello_world_wasm2js': ('hello_world', True),
+    'hello_world_wasm': ('hello_world', False, True),
+    'hello_world_wasm2js': ('hello_world', True, True),
     'random_printf_wasm': ('random_printf', False),
     'random_printf_wasm2js': ('random_printf', True),
     'hello_webgl_wasm': ('hello_webgl', False),
     'hello_webgl_wasm2js': ('hello_webgl', True),
     'hello_webgl2_wasm': ('hello_webgl2', False),
     'hello_webgl2_wasm2js': ('hello_webgl2', True),
   })
-  def test_minimal_runtime_code_size(self, test_name, js):
+  def test_minimal_runtime_code_size(self, test_name, js, compare_js_output=False):
     smallest_code_size_args = ['-s', 'MINIMAL_RUNTIME=2',
                                '-s', 'ENVIRONMENT=web',
                                '-s', 'TEXTDECODER=2',
@@ -8286,6 +8286,21 @@ def get_file_gzipped_size(f):
       try_delete(f_gz)
       return size
 
+    # For certain tests, don't just check the output size but check
+    # the full JS output matches the expectations.  That means that
+    # any change that touches those core lines of output will need
+    # to rebaseline this test.  However:
+    # a) such changes deserve extra scrutiny
+    # b) such changes should be few and far between
+    # c) rebaselining is trivial (just run with EMTEST_REBASELINE=1)
+    # Note that we do not compare the full wasm output since that is
+    # even more fragile and can change with LLVM updates.
+    if compare_js_output:
+      js_out = path_from_root('tests', 'code_size', test_name + '.js')
+      terser = shared.get_npm_cmd('terser')
+      self.run_process(terser + ['-b', 'beautify=true', 'a.js', '-o', 'pretty.js'])
+      self.assertFileContents(js_out, open('pretty.js').read())
+
     obtained_results = {}
     total_output_size = 0
     total_expected_size = 0