feat(terser): support .map files in directory inputs

packages/terser/src/index.js

@@ -29,19 +29,27 @@ function isDirectory(input) {
 /**
  * Replaces directory url with the outputFile name in the url option of source-map argument
  */
-function directoryArgs(residualArgs, outputFile) {
+function directoryArgs(residualArgs, inputFile, outputFile) {
   const sourceMapIndex = residualArgs.indexOf('--source-map');
   if (sourceMapIndex === -1) {
     return residualArgs;
   }
 
-  const sourceMapOptions = residualArgs[sourceMapIndex + 1].split(',');
-  const newSourceMapOptions = sourceMapOptions.map(
+  // set the correct sourcemap url for this output file
+  let sourceMapOptions = residualArgs[sourceMapIndex + 1].split(',').map(
       o => o.startsWith('url=') ? `url='${path.basename(outputFile)}.map'` : o);
 
+  // if an input .map file exists then set the correct sourcemap content option
+  if (fs.existsSync(`${inputFile}.map`)) {
+    // even on Windows terser expects '/' path separators so we normalize these in the sourcemap
+    // content file path below
+    sourceMapOptions = sourceMapOptions.map(
+        o => o.startsWith('content=') ? `content='${inputFile.replace(/\\/g, '/')}.map'` : o);
+  }
+
   return [
     ...residualArgs.slice(0, sourceMapIndex + 1),
-    newSourceMapOptions.join(','),
+    sourceMapOptions.join(','),
     ...residualArgs.slice(sourceMapIndex + 2),
   ];
 }
@@ -59,8 +67,10 @@ function terserDirectory(input, output, residual, terserBinary) {
 
   function exec([inputFile, outputFile]) {
     active++;
-    let args =
-        [terserBinary, inputFile, '--output', outputFile, ...directoryArgs(residual, outputFile)];
+    let args = [
+      terserBinary, inputFile, '--output', outputFile,
+      ...directoryArgs(residual, inputFile, outputFile)
+    ];
 
     spawn(process.execPath, args)
         .then(

packages/terser/test/BUILD.bazel

@@ -3,5 +3,8 @@ load("@npm_bazel_jasmine//:index.from_src.bzl", "jasmine_node_test")
 jasmine_node_test(
     name = "test",
     srcs = ["directory-args.spec.js"],
-    deps = ["@npm_bazel_terser//:index.js"],
+    deps = [
+        "@npm//tmp",
+        "@npm_bazel_terser//:index.js",
+    ],
 )

packages/terser/test/directory-args.spec.js

@@ -1,8 +1,11 @@
 const {directoryArgs} = require('npm_bazel_terser/index')
+const fs = require('fs');
+const path = require('path');
+const tmp = require('tmp');
 
 describe('directoryArgs', () => {
   it('return a new array ref', () => {
-    const args = ['--source-map', ''];
+    const args = ['--source-map', '', ''];
     expect(directoryArgs(args, '')).not.toBe(args);
   });
 
@@ -11,18 +14,32 @@ describe('directoryArgs', () => {
     expect(directoryArgs(args)).toBe(args);
   });
 
-  it('should replace the directory url with the file url', () => {
+  it('should set the correct file url and souremap content', () => {
+    const out = tmp.dirSync().name;
+    const input = path.join(out, 'file.js');
+    const output = '/test/file.js';
     const args = [
       '--ie8',
       '--source-map',
-      `root='http://foo.com/src',url='some_wrong_name'`,
+      `root='http://foo.com/src',url='some_wrong_name',content=inline`,
       '--keep-fnames',
     ];
-    const output = '/test/file.js';
-    expect(directoryArgs(args, output)).toEqual([
+    // if no corresponding map file exists then sourcemap content should
+    // be left as inline
+    expect(directoryArgs(args, input, output)).toEqual([
+      '--ie8',
+      '--source-map',
+      `root='http://foo.com/src',url='${path.basename(output)}.map',content=inline`,
+      '--keep-fnames',
+    ]);
+    // if a corresponding map file exists then sourcemap content should be set
+    // to the  map file
+    fs.writeFileSync(`${input}.map`, '');
+    expect(directoryArgs(args, input, output)).toEqual([
       '--ie8',
       '--source-map',
-      `root='http://foo.com/src',url='file.js.map'`,
+      `root='http://foo.com/src',url='${path.basename(output)}.map',content='${
+          input.replace(/\\/g, '/')}.map'`,
       '--keep-fnames',
     ]);
   });

packages/terser/test/directory_input/BUILD.bazel

@@ -1,8 +1,7 @@
+load("@build_bazel_rules_nodejs//:tools/declare_directory.bzl", "declare_directory")
 load("@npm_bazel_jasmine//:index.from_src.bzl", "jasmine_node_test")
 load("@npm_bazel_terser//:index.from_src.bzl", "terser_minified")
-load(":rule.bzl", "declare_directory")
 
-# Check that filegroups work
 declare_directory(
     name = "dir",
     srcs = glob(["input*.js"]),

packages/terser/test/sourcemap/BUILD.bazel

@@ -1,3 +1,4 @@
+load("@build_bazel_rules_nodejs//:tools/declare_directory.bzl", "declare_directory")
 load("@npm_bazel_jasmine//:index.from_src.bzl", "jasmine_node_test")
 load("@npm_bazel_terser//:index.from_src.bzl", "terser_minified")
 
@@ -24,3 +25,27 @@ jasmine_node_test(
         ":src1.min",
     ],
 )
+
+declare_directory(
+    name = "dir",
+    srcs = [
+        "src1.js",
+        "src1.js.map",
+    ],
+)
+
+terser_minified(
+    name = "dir.min",
+    src = "dir",
+)
+
+jasmine_node_test(
+    name = "directory_test",
+    srcs = [
+        "directory_spec.js",
+    ],
+    data = ["@npm//source-map"],
+    deps = [
+        ":dir.min",
+    ],
+)

packages/terser/test/sourcemap/directory_spec.js

@@ -0,0 +1,27 @@
+const fs = require('fs');
+const sm = require('source-map');
+const path = require('path');
+const {runfiles} = require('build_bazel_rules_nodejs/internal/linker');
+
+describe('terser on a directory with map files', () => {
+  it('should produce an output for each input', () => {
+    const out = runfiles.resolvePackageRelative('dir.min');
+    expect(fs.existsSync(out + '/src1.js')).toBeTruthy();
+  });
+
+  it('should produce a sourcemap output', async () => {
+    const out = runfiles.resolvePackageRelative('dir.min');
+    const file = require.resolve(out + '/src1.js.map');
+    const rawSourceMap = JSON.parse(fs.readFileSync(file, 'utf-8'));
+    await sm.SourceMapConsumer.with(rawSourceMap, null, consumer => {
+      const pos = consumer.originalPositionFor(
+          // position of MyClass in terser_minified output src1.min.js
+          // depends on DEBUG flag
+          !process.env['DEBUG'] ? {line: 1, column: 18} : {line: 3, column: 5});
+      expect(pos.source).toBe('src1.ts');
+      expect(pos.line).toBe(2);
+      expect(pos.column).toBe(14);
+      expect(pos.name).toBe('MyClass');
+    });
+  });
+});