feat(rollup): ensure that sourcemaps work end-to-end

examples/BUILD.bazel

@@ -87,6 +87,7 @@ example_integration_test(
 example_integration_test(
     name = "examples_webapp",
     npm_packages = {
+        "//packages/jasmine:npm_package": "@bazel/jasmine",
         "//packages/protractor:npm_package": "@bazel/protractor",
         "//packages/rollup:npm_package": "@bazel/rollup",
         "//packages/terser:npm_package": "@bazel/terser",

examples/webapp/BUILD.bazel

@@ -1,4 +1,5 @@
 load("@npm//http-server:index.bzl", "http_server")
+load("@npm_bazel_jasmine//:index.bzl", "jasmine_node_test")
 load("@npm_bazel_protractor//:index.bzl", "protractor_web_test_suite")
 load(":differential_loading.bzl", "differential_loading")
 
@@ -30,10 +31,16 @@ protractor_web_test_suite(
     ],
 )
 
-# Just a dummy test so that we have a test target for //... on certain bazelci platforms with bazel_integration_test
-sh_test(
-    name = "dummy_test",
-    srcs = ["dummy_test.sh"],
+jasmine_node_test(
+    name = "test_sourcemaps",
+    srcs = ["sourcemaps.spec.js"],
+    deps = [
+        ":app_chunks",
+        ":app_chunks.min",
+        ":app_chunks_es5",
+        ":app_chunks_es5.min",
+        "@npm//source-map",
+    ],
 )
 
 # For testing from the root workspace of this repository with bazel_integration_test.

examples/webapp/differential_loading.bzl

@@ -12,6 +12,7 @@ def differential_loading(name, entry_point, srcs):
     rollup_bundle(
         name = name + "_chunks",
         srcs = srcs,
+        sourcemap = "inline",
         entry_points = {
             entry_point: "index",
         },

examples/webapp/es5.babelrc

@@ -1,4 +1,5 @@
 {
+  "sourceMaps": "inline",
   "presets": [
     [
       "@babel/preset-env",

examples/webapp/index.js

@@ -2,6 +2,7 @@
 import('./strings.en').then(m => {
     const msg = document.createElement('div');
     msg.innerText = m.hello();
+    // For sourcemap testing, keep this string literal on line 6 column 21 !!
     msg.className = 'ts1';
     document.body.appendChild(msg);
 });

examples/webapp/package.json

@@ -4,12 +4,14 @@
         "@babel/cli": "^7.6.0",
         "@babel/core": "^7.6.0",
         "@babel/preset-env": "^7.6.0",
-        "@bazel/rollup": "latest",
-        "@bazel/terser": "latest",
-        "@bazel/protractor": "latest",
+        "@bazel/jasmine": "^0.37.1",
+        "@bazel/protractor": "file:/tmp/tmp-164023L7r1MgY0dmka",
+        "@bazel/rollup": "file:/tmp/tmp-164023xwqtzUemMOVT",
+        "@bazel/terser": "file:/tmp/tmp-164023K73Ev0H45uDb",
         "http-server": "^0.11.1",
-        "terser": "^4.3.1",
-        "rollup": "1.21.4"
+        "rollup": "1.21.4",
+        "source-map": "^0.7.3",
+        "terser": "^4.3.1"
     },
     "scripts": {
         "test": "bazel test ..."

examples/webapp/sourcemaps.spec.js

@@ -0,0 +1,78 @@
+// Ensure we have working sourcemaps when the app runs in a browser
+
+const fs = require('fs');
+const path = require('path');
+const sm = require('source-map');
+
+const PRAGMA = '//# sourceMappingURL=';
+const DATA = 'data:application/json;charset=utf-8;base64,';
+
+function read(...f) {
+  return fs.readFileSync(require.resolve(path.join(__dirname, ...f)), 'utf-8');
+}
+
+function parseSourceMap(content) {
+  const sourcemapLine = content.split(/\r?\n/).find(l => l.startsWith(PRAGMA));
+  if (!sourcemapLine) {
+    throw new Error(`no ${PRAGMA} found in ${content}`);
+  }
+  return JSON.parse(Buffer.from(sourcemapLine.slice(PRAGMA.length + DATA.length), 'base64'));
+}
+
+function readSourceMap(...f) {
+  return JSON.parse(fs.readFileSync(require.resolve(path.join(__dirname, ...f))));
+}
+
+function find(text, s = 'ts1') {
+  const lines = text.split(/\r?\n/);
+  for (let line = 1; line <= lines.length; line++) {
+    const column = lines[line - 1].indexOf(s);
+    if (column >= 0) {
+      return {line, column};
+    }
+  }
+}
+
+function asserts(pos) {
+  // This doesn't work because the output dir is different from input
+  // so it actually starts with a bunch of '/../..'
+  // expect(pos.source).toBe('index.js');
+
+  expect(pos.source.endsWith('index.js')).toBeTruthy();
+  expect(pos.line).toBe(6);     // one-based
+  expect(pos.column).toBe(20);  // zero-based
+}
+
+describe('application sourcemaps in the browser', () => {
+  it('should work after rollup', async () => {
+    const content = read('app_chunks', 'index.js');
+    const rawSourceMap = parseSourceMap(content);
+    await sm.SourceMapConsumer.with(rawSourceMap, null, consumer => {
+      asserts(consumer.originalPositionFor(find(content)));
+    });
+  });
+
+  it('should work after terser', async () => {
+    const content = read('app_chunks.min', 'index.js');
+    const rawSourceMap = readSourceMap('app_chunks.min', 'index.js.map');
+    await sm.SourceMapConsumer.with(rawSourceMap, null, consumer => {
+      asserts(consumer.originalPositionFor(find(content)));
+    });
+  });
+
+  it('should work after babel', async () => {
+    const content = read('app_chunks_es5', 'index.js');
+    const rawSourceMap = parseSourceMap(content);
+    await sm.SourceMapConsumer.with(rawSourceMap, null, consumer => {
+      asserts(consumer.originalPositionFor(find(content)));
+    });
+  });
+
+  it('should work after babel+terser', async () => {
+    const content = read('app_chunks_es5.min', 'index.js');
+    const rawSourceMap = readSourceMap('app_chunks_es5.min', 'index.js.map');
+    await sm.SourceMapConsumer.with(rawSourceMap, null, consumer => {
+      asserts(consumer.originalPositionFor(find(content)));
+    });
+  });
+});

packages/rollup/src/rollup_bundle.bzl

@@ -148,12 +148,13 @@ Otherwise, the outputs are assumed to be a single file.
         cfg = "host",
         default = "@npm//rollup/bin:rollup",
     ),
-    "sourcemap": attr.bool(
-        doc = """Whether to produce a .js.map output
+    "sourcemap": attr.string(
+        doc = """Whether to produce sourcemaps.
 
 Passed to the [`--sourcemap` option](https://github.com/rollup/rollup/blob/master/docs/999-big-list-of-options.md#outputsourcemap") in Rollup
 """,
-        default = True,
+        default = "inline",
+        values = ["inline", "true", "false"],
     ),
     "deps": attr.label_list(
         aspects = [module_mappings_aspect],
@@ -218,7 +219,7 @@ def _rollup_outs(sourcemap, name, entry_point, entry_points, output_dir):
             fail("Multiple entry points require that output_dir be set")
         out = entry_point_outs[0]
         result[out] = out + ".js"
-        if sourcemap:
+        if sourcemap == "true":
             result[out + "_map"] = "%s.map" % result[out]
     return result
 
@@ -273,8 +274,8 @@ def _rollup_bundle(ctx):
     # where the link is.
     args.add("--preserveSymlinks")
 
-    if (ctx.attr.sourcemap):
-        args.add("--sourcemap")
+    if (ctx.attr.sourcemap and ctx.attr.sourcemap != "false"):
+        args.add_all(["--sourcemap", ctx.attr.sourcemap])
 
     if ctx.attr.globals:
         args.add("--external")

packages/rollup/test/globals/BUILD.bazel

@@ -6,7 +6,7 @@ rollup_bundle(
     entry_point = "input.js",
     format = "umd",
     globals = {"some_global_var": "runtime_name_of_global_var"},
-    sourcemap = False,
+    sourcemap = "false",
 )
 
 golden_file_test(

packages/rollup/test/integration_e2e_rollup/BUILD.bazel

@@ -9,6 +9,7 @@ load("@npm_bazel_rollup//:index.from_src.bzl", "rollup_bundle")
         entry_point = "foo.js",
         format = format,
         globals = {"some_global_var": "runtime_name_of_global_var"},
+        sourcemap = "true",
         deps = [
             "//%s/fum:fumlib" % package_name(),
             "@npm//hello",

packages/rollup/test/plugins/BUILD.bazel

@@ -6,7 +6,7 @@ rollup_bundle(
     srcs = ["some.json"],
     config_file = "rollup.config.js",
     entry_point = "input.js",
-    sourcemap = False,
+    sourcemap = "false",
 )
 
 golden_file_test(

packages/rollup/test/sourcemaps/BUILD.bazel

@@ -6,6 +6,7 @@ rollup_bundle(
     srcs = ["s.js"],
     # Use the desugared form to assert that it works
     entry_points = {"input.js": "bundle"},
+    sourcemap = "true",
 )
 
 jasmine_node_test(

packages/rollup/test/version_stamp/BUILD.bazel

@@ -5,8 +5,7 @@ rollup_bundle(
     name = "version_stamp",
     config_file = "rollup.config.js",
     entry_point = "input.js",
-    # Disable sourcemap so we only get a single output
-    sourcemap = False,
+    sourcemap = "false",
 )
 
 golden_file_test(