fix: do not run parallel mode when you have only one file (#134)

src/TaskRunner.js

@@ -43,7 +43,7 @@ export default class TaskRunner {
       return;
     }
 
-    if (this.maxConcurrentWorkers > 1) {
+    if (this.maxConcurrentWorkers > 1 && tasks.length > 1) {
       const workerOptions =
         process.platform === 'win32'
           ? {

test/__snapshots__/parallel-option-failure.test.js.snap

@@ -3,6 +3,8 @@
 exports[`parallel option should match snapshot for errors into the "worker-farm" package whe the "cache" option is "true": errors 1`] = `
 Array [
   "Error: one.js from Terser
+Error: worker-farm failed",
+  "Error: two.js from Terser
 Error: worker-farm failed",
 ]
 `;
@@ -12,6 +14,8 @@ exports[`parallel option should match snapshot for errors into the "worker-farm"
 exports[`parallel option should match snapshot for errors into the "worker-farm" package: errors 1`] = `
 Array [
   "Error: one.js from Terser
+Error: worker-farm failed",
+  "Error: two.js from Terser
 Error: worker-farm failed",
 ]
 `;

test/__snapshots__/parallel-option.test.js.snap

@@ -1,5 +1,9 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`parallel option should match snapshot for errors into the "worker-farm" package: errors 1`] = `Array []`;
+
+exports[`parallel option should match snapshot for errors into the "worker-farm" package: warnings 1`] = `Array []`;
+
 exports[`parallel option should match snapshot for the "2" value: assets 1`] = `
 Object {
   "four.js": "!function(e){var t={};function n(r){if(t[r])return t[r].exports;var o=t[r]={i:r,l:!1,exports:{}};return e[r].call(o.exports,o,o.exports,n),o.l=!0,o.exports}n.m=e,n.c=t,n.d=function(e,t,r){n.o(e,t)||Object.defineProperty(e,t,{enumerable:!0,get:r})},n.r=function(e){\\"undefined\\"!=typeof Symbol&&Symbol.toStringTag&&Object.defineProperty(e,Symbol.toStringTag,{value:\\"Module\\"}),Object.defineProperty(e,\\"__esModule\\",{value:!0})},n.t=function(e,t){if(1&t&&(e=n(e)),8&t)return e;if(4&t&&\\"object\\"==typeof e&&e&&e.__esModule)return e;var r=Object.create(null);if(n.r(r),Object.defineProperty(r,\\"default\\",{enumerable:!0,value:e}),2&t&&\\"string\\"!=typeof e)for(var o in e)n.d(r,o,function(t){return e[t]}.bind(null,o));return r},n.n=function(e){var t=e&&e.__esModule?function(){return e.default}:function(){return e};return n.d(t,\\"a\\",t),t},n.o=function(e,t){return Object.prototype.hasOwnProperty.call(e,t)},n.p=\\"\\",n(n.s=0)}([function(e,t){e.exports=function(){console.log(7)}}]);",
@@ -26,6 +30,27 @@ exports[`parallel option should match snapshot for the "false" value: errors 1`]
 
 exports[`parallel option should match snapshot for the "false" value: warnings 1`] = `Array []`;
 
+exports[`parallel option should match snapshot for the "true" value and only one file passed: assets 1`] = `
+Object {
+  "main.js": "!function(e){var t={};function n(r){if(t[r])return t[r].exports;var o=t[r]={i:r,l:!1,exports:{}};return e[r].call(o.exports,o,o.exports,n),o.l=!0,o.exports}n.m=e,n.c=t,n.d=function(e,t,r){n.o(e,t)||Object.defineProperty(e,t,{enumerable:!0,get:r})},n.r=function(e){\\"undefined\\"!=typeof Symbol&&Symbol.toStringTag&&Object.defineProperty(e,Symbol.toStringTag,{value:\\"Module\\"}),Object.defineProperty(e,\\"__esModule\\",{value:!0})},n.t=function(e,t){if(1&t&&(e=n(e)),8&t)return e;if(4&t&&\\"object\\"==typeof e&&e&&e.__esModule)return e;var r=Object.create(null);if(n.r(r),Object.defineProperty(r,\\"default\\",{enumerable:!0,value:e}),2&t&&\\"string\\"!=typeof e)for(var o in e)n.d(r,o,function(t){return e[t]}.bind(null,o));return r},n.n=function(e){var t=e&&e.__esModule?function(){return e.default}:function(){return e};return n.d(t,\\"a\\",t),t},n.o=function(e,t){return Object.prototype.hasOwnProperty.call(e,t)},n.p=\\"\\",n(n.s=0)}([function(e,t){e.exports=function(){console.log(7)}}]);",
+}
+`;
+
+exports[`parallel option should match snapshot for the "true" value and only one file passed: errors 1`] = `Array []`;
+
+exports[`parallel option should match snapshot for the "true" value and only one file passed: warnings 1`] = `Array []`;
+
+exports[`parallel option should match snapshot for the "true" value and two files passed: assets 1`] = `
+Object {
+  "one.js": "!function(e){var t={};function n(r){if(t[r])return t[r].exports;var o=t[r]={i:r,l:!1,exports:{}};return e[r].call(o.exports,o,o.exports,n),o.l=!0,o.exports}n.m=e,n.c=t,n.d=function(e,t,r){n.o(e,t)||Object.defineProperty(e,t,{enumerable:!0,get:r})},n.r=function(e){\\"undefined\\"!=typeof Symbol&&Symbol.toStringTag&&Object.defineProperty(e,Symbol.toStringTag,{value:\\"Module\\"}),Object.defineProperty(e,\\"__esModule\\",{value:!0})},n.t=function(e,t){if(1&t&&(e=n(e)),8&t)return e;if(4&t&&\\"object\\"==typeof e&&e&&e.__esModule)return e;var r=Object.create(null);if(n.r(r),Object.defineProperty(r,\\"default\\",{enumerable:!0,value:e}),2&t&&\\"string\\"!=typeof e)for(var o in e)n.d(r,o,function(t){return e[t]}.bind(null,o));return r},n.n=function(e){var t=e&&e.__esModule?function(){return e.default}:function(){return e};return n.d(t,\\"a\\",t),t},n.o=function(e,t){return Object.prototype.hasOwnProperty.call(e,t)},n.p=\\"\\",n(n.s=0)}([function(e,t){e.exports=function(){console.log(7)}}]);",
+  "two.js": "!function(e){var t={};function n(r){if(t[r])return t[r].exports;var o=t[r]={i:r,l:!1,exports:{}};return e[r].call(o.exports,o,o.exports,n),o.l=!0,o.exports}n.m=e,n.c=t,n.d=function(e,t,r){n.o(e,t)||Object.defineProperty(e,t,{enumerable:!0,get:r})},n.r=function(e){\\"undefined\\"!=typeof Symbol&&Symbol.toStringTag&&Object.defineProperty(e,Symbol.toStringTag,{value:\\"Module\\"}),Object.defineProperty(e,\\"__esModule\\",{value:!0})},n.t=function(e,t){if(1&t&&(e=n(e)),8&t)return e;if(4&t&&\\"object\\"==typeof e&&e&&e.__esModule)return e;var r=Object.create(null);if(n.r(r),Object.defineProperty(r,\\"default\\",{enumerable:!0,value:e}),2&t&&\\"string\\"!=typeof e)for(var o in e)n.d(r,o,function(t){return e[t]}.bind(null,o));return r},n.n=function(e){var t=e&&e.__esModule?function(){return e.default}:function(){return e};return n.d(t,\\"a\\",t),t},n.o=function(e,t){return Object.prototype.hasOwnProperty.call(e,t)},n.p=\\"\\",n(n.s=0)}([function(e,t){e.exports=function(){console.log(7)}}]);",
+}
+`;
+
+exports[`parallel option should match snapshot for the "true" value and two files passed: errors 1`] = `Array []`;
+
+exports[`parallel option should match snapshot for the "true" value and two files passed: warnings 1`] = `Array []`;
+
 exports[`parallel option should match snapshot for the "true" value: assets 1`] = `
 Object {
   "four.js": "!function(e){var t={};function n(r){if(t[r])return t[r].exports;var o=t[r]={i:r,l:!1,exports:{}};return e[r].call(o.exports,o,o.exports,n),o.l=!0,o.exports}n.m=e,n.c=t,n.d=function(e,t,r){n.o(e,t)||Object.defineProperty(e,t,{enumerable:!0,get:r})},n.r=function(e){\\"undefined\\"!=typeof Symbol&&Symbol.toStringTag&&Object.defineProperty(e,Symbol.toStringTag,{value:\\"Module\\"}),Object.defineProperty(e,\\"__esModule\\",{value:!0})},n.t=function(e,t){if(1&t&&(e=n(e)),8&t)return e;if(4&t&&\\"object\\"==typeof e&&e&&e.__esModule)return e;var r=Object.create(null);if(n.r(r),Object.defineProperty(r,\\"default\\",{enumerable:!0,value:e}),2&t&&\\"string\\"!=typeof e)for(var o in e)n.d(r,o,function(t){return e[t]}.bind(null,o));return r},n.n=function(e){var t=e&&e.__esModule?function(){return e.default}:function(){return e};return n.d(t,\\"a\\",t),t},n.o=function(e,t){return Object.prototype.hasOwnProperty.call(e,t)},n.p=\\"\\",n(n.s=0)}([function(e,t){e.exports=function(){console.log(7)}}]);",

test/parallel-option-failure.test.js

@@ -48,6 +48,7 @@ describe('parallel option', () => {
     compiler = createCompiler({
       entry: {
         one: `${__dirname}/fixtures/entry.js`,
+        two: `${__dirname}/fixtures/entry.js`,
       },
     });
 

test/parallel-option.test.js

@@ -140,4 +140,71 @@ describe('parallel option', () => {
     expect(warnings).toMatchSnapshot('warnings');
     expect(getAssets(stats, compiler)).toMatchSnapshot('assets');
   });
+
+  it('should match snapshot for the "true" value and only one file passed', async () => {
+    compiler = createCompiler({
+      entry: `${__dirname}/fixtures/entry.js`,
+    });
+
+    new TerserPlugin({ parallel: true }).apply(compiler);
+
+    const stats = await compile(compiler);
+
+    const errors = stats.compilation.errors.map(cleanErrorStack);
+    const warnings = stats.compilation.warnings.map(cleanErrorStack);
+
+    expect(workerFarm.mock.calls.length).toBe(0);
+    expect(workerFarm.end.mock.calls.length).toBe(0);
+
+    expect(errors).toMatchSnapshot('errors');
+    expect(warnings).toMatchSnapshot('warnings');
+    expect(getAssets(stats, compiler)).toMatchSnapshot('assets');
+  });
+
+  it('should match snapshot for the "true" value and two files passed', async () => {
+    compiler = createCompiler({
+      entry: {
+        one: `${__dirname}/fixtures/entry.js`,
+        two: `${__dirname}/fixtures/entry.js`,
+      },
+    });
+
+    new TerserPlugin({ parallel: true }).apply(compiler);
+
+    const stats = await compile(compiler);
+
+    const errors = stats.compilation.errors.map(cleanErrorStack);
+    const warnings = stats.compilation.warnings.map(cleanErrorStack);
+
+    expect(workerFarm.mock.calls.length).toBe(1);
+    expect(workerFarm.mock.calls[0][0].maxConcurrentWorkers).toBe(
+      os.cpus().length - 1
+    );
+    expect(workerFarmMock.mock.calls.length).toBe(
+      Object.keys(stats.compilation.assets).length
+    );
+    expect(workerFarm.end.mock.calls.length).toBe(1);
+
+    expect(errors).toMatchSnapshot('errors');
+    expect(warnings).toMatchSnapshot('warnings');
+    expect(getAssets(stats, compiler)).toMatchSnapshot('assets');
+  });
+
+  it('should match snapshot for errors into the "worker-farm" package', async () => {
+    new TerserPlugin({ parallel: true, cache: false }).apply(compiler);
+
+    const stats = await compile(compiler);
+
+    const errors = stats.compilation.errors.map(cleanErrorStack);
+    const warnings = stats.compilation.warnings.map(cleanErrorStack);
+
+    expect(workerFarm.mock.calls.length).toBe(1);
+    expect(workerFarmMock.mock.calls.length).toBe(
+      Object.keys(stats.compilation.assets).length
+    );
+    expect(workerFarm.end.mock.calls.length).toBe(1);
+
+    expect(errors).toMatchSnapshot('errors');
+    expect(warnings).toMatchSnapshot('warnings');
+  });
 });