From 6950b1eb38964877742a408f3289473c4abb5067 Mon Sep 17 00:00:00 2001
From: Tim Seckinger <seckinger.tim@gmail.com>
Date: Wed, 26 Dec 2018 14:24:11 +0100
Subject: [PATCH 1/5] dependency_resolver.test.js describe blocks

---
 .../src/__tests__/dependency_resolver.test.js | 111 ++++++++++--------
 1 file changed, 59 insertions(+), 52 deletions(-)

diff --git a/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js b/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js
index 3725c9bc951f..1af936b7aaed 100644
--- a/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js
+++ b/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js
@@ -40,66 +40,73 @@ beforeEach(() => {
   });
 });
 
-test('resolves no dependencies for non-existent path', () => {
-  const resolved = dependencyResolver.resolve('/non/existent/path');
-  expect(resolved.length).toEqual(0);
-});
-
-test('resolves dependencies for existing path', () => {
-  const resolved = dependencyResolver.resolve(
-    path.resolve(__dirname, '__fixtures__', 'file.js'),
-  );
-  expect(resolved).toEqual([
-    expect.stringContaining('jest-resolve-dependencies'),
-    expect.stringContaining('jest-regex-util'),
-  ]);
-});
+describe('resolve', () => {
+  test('resolves no dependencies for non-existent path', () => {
+    const resolved = dependencyResolver.resolve('/non/existent/path');
+    expect(resolved.length).toEqual(0);
+  });
 
-test('resolves dependencies for scoped packages', () => {
-  const resolved = dependencyResolver.resolve(
-    path.resolve(__dirname, '__fixtures__', 'scoped.js'),
-  );
-  expect(resolved).toEqual([
-    expect.stringContaining(path.join('@myorg', 'pkg')),
-  ]);
-});
+  test('resolves dependencies for existing path', () => {
+    const resolved = dependencyResolver.resolve(
+      path.resolve(__dirname, '__fixtures__', 'file.js'),
+    );
+    expect(resolved).toEqual([
+      expect.stringContaining('jest-resolve-dependencies'),
+      expect.stringContaining('jest-regex-util'),
+    ]);
+  });
 
-test('resolves no inverse dependencies for empty paths set', () => {
-  const paths = new Set();
-  const resolved = dependencyResolver.resolveInverse(paths, filter);
-  expect(resolved.length).toEqual(0);
+  test('resolves dependencies for scoped packages', () => {
+    const resolved = dependencyResolver.resolve(
+      path.resolve(__dirname, '__fixtures__', 'scoped.js'),
+    );
+    expect(resolved).toEqual([
+      expect.stringContaining(path.join('@myorg', 'pkg')),
+    ]);
+  });
 });
 
-test('resolves no inverse dependencies for set of non-existent paths', () => {
-  const paths = new Set(['/non/existent/path', '/another/one']);
-  const resolved = dependencyResolver.resolveInverse(paths, filter);
-  expect(resolved.length).toEqual(0);
-});
+describe('resolveInverse', () => {
+  test('resolves no inverse dependencies for empty paths set', () => {
+    const paths = new Set();
+    const resolved = dependencyResolver.resolveInverse(paths, filter);
+    expect(resolved.length).toEqual(0);
+  });
 
-test('resolves inverse dependencies for existing path', () => {
-  const paths = new Set([path.resolve(__dirname, '__fixtures__/file.js')]);
-  const resolved = dependencyResolver.resolveInverse(paths, filter);
-  expect(resolved).toEqual([
-    expect.stringContaining(
-      path.join('__tests__', '__fixtures__', 'file.test.js'),
-    ),
-  ]);
-});
+  test('resolves no inverse dependencies for set of non-existent paths', () => {
+    const paths = new Set(['/non/existent/path', '/another/one']);
+    const resolved = dependencyResolver.resolveInverse(paths, filter);
+    expect(resolved.length).toEqual(0);
+  });
 
-test('resolves inverse dependencies from available snapshot', () => {
-  const paths = new Set([
-    path.resolve(__dirname, '__fixtures__/file.js'),
-    path.resolve(__dirname, '__fixtures__/__snapshots__/related.test.js.snap'),
-  ]);
-  const resolved = dependencyResolver.resolveInverse(paths, filter);
-  expect(resolved).toEqual(
-    expect.arrayContaining([
+  test('resolves inverse dependencies for existing path', () => {
+    const paths = new Set([path.resolve(__dirname, '__fixtures__/file.js')]);
+    const resolved = dependencyResolver.resolveInverse(paths, filter);
+    expect(resolved).toEqual([
       expect.stringContaining(
         path.join('__tests__', '__fixtures__', 'file.test.js'),
       ),
-      expect.stringContaining(
-        path.join('__tests__', '__fixtures__', 'related.test.js'),
+    ]);
+  });
+
+  test('resolves inverse dependencies from available snapshot', () => {
+    const paths = new Set([
+      path.resolve(__dirname, '__fixtures__/file.js'),
+      path.resolve(
+        __dirname,
+        '__fixtures__/__snapshots__/related.test.js.snap',
       ),
-    ]),
-  );
+    ]);
+    const resolved = dependencyResolver.resolveInverse(paths, filter);
+    expect(resolved).toEqual(
+      expect.arrayContaining([
+        expect.stringContaining(
+          path.join('__tests__', '__fixtures__', 'file.test.js'),
+        ),
+        expect.stringContaining(
+          path.join('__tests__', '__fixtures__', 'related.test.js'),
+        ),
+      ]),
+    );
+  });
 });

From 47d5477f13b39c21f00d7daba74909223981f43f Mon Sep 17 00:00:00 2001
From: Tim Seckinger <seckinger.tim@gmail.com>
Date: Wed, 26 Dec 2018 14:28:04 +0100
Subject: [PATCH 2/5] add DependencyResolver.resolveRecursive()

---
 CHANGELOG.md                                  |  2 ++
 .../src/__tests__/__fixtures__/circular/a.js  | 10 ++++++
 .../src/__tests__/__fixtures__/circular/b.js  | 10 ++++++
 .../src/__tests__/__fixtures__/circular/c.js  | 10 ++++++
 .../src/__tests__/__fixtures__/recursive/a.js | 10 ++++++
 .../src/__tests__/__fixtures__/recursive/b.js | 11 ++++++
 .../__tests__/__fixtures__/recursive/c1.js    |  8 +++++
 .../__tests__/__fixtures__/recursive/c2.js    |  8 +++++
 .../src/__tests__/dependency_resolver.test.js | 34 +++++++++++++++++--
 .../jest-resolve-dependencies/src/index.js    | 21 ++++++++++--
 10 files changed, 119 insertions(+), 5 deletions(-)
 create mode 100644 packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/a.js
 create mode 100644 packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/b.js
 create mode 100644 packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/c.js
 create mode 100644 packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/a.js
 create mode 100644 packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/b.js
 create mode 100644 packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/c1.js
 create mode 100644 packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/c2.js

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0050a9f04365..7aca48592cc8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ### Features
 
+- `[jest-resolve-dependencies]` Add `DependencyResolver.resolveRecursive` ([#7553](https://github.com/facebook/jest/pull/7553))
+
 ### Fixes
 
 - `[jest-cli]` Refactor `-o` and `--coverage` combined ([#7611](https://github.com/facebook/jest/pull/7611))
diff --git a/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/a.js b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/a.js
new file mode 100644
index 000000000000..29a5470d6c56
--- /dev/null
+++ b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/a.js
@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+'use strict';
+
+require('./b');
diff --git a/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/b.js b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/b.js
new file mode 100644
index 000000000000..db51e2149010
--- /dev/null
+++ b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/b.js
@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+'use strict';
+
+require('./c');
diff --git a/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/c.js b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/c.js
new file mode 100644
index 000000000000..79cdb76ea1d6
--- /dev/null
+++ b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/circular/c.js
@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+'use strict';
+
+require('./a');
diff --git a/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/a.js b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/a.js
new file mode 100644
index 000000000000..29a5470d6c56
--- /dev/null
+++ b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/a.js
@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+'use strict';
+
+require('./b');
diff --git a/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/b.js b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/b.js
new file mode 100644
index 000000000000..ede9730e2a30
--- /dev/null
+++ b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/b.js
@@ -0,0 +1,11 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+'use strict';
+
+require('./c1');
+require('./c2');
diff --git a/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/c1.js b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/c1.js
new file mode 100644
index 000000000000..3d797dae3666
--- /dev/null
+++ b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/c1.js
@@ -0,0 +1,8 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+'use strict';
diff --git a/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/c2.js b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/c2.js
new file mode 100644
index 000000000000..3d797dae3666
--- /dev/null
+++ b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/recursive/c2.js
@@ -0,0 +1,8 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+'use strict';
diff --git a/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js b/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js
index 1af936b7aaed..b8406f5e849d 100644
--- a/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js
+++ b/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js
@@ -43,7 +43,7 @@ beforeEach(() => {
 describe('resolve', () => {
   test('resolves no dependencies for non-existent path', () => {
     const resolved = dependencyResolver.resolve('/non/existent/path');
-    expect(resolved.length).toEqual(0);
+    expect(resolved).toHaveLength(0);
   });
 
   test('resolves dependencies for existing path', () => {
@@ -66,17 +66,45 @@ describe('resolve', () => {
   });
 });
 
+describe('resolveRecursive', () => {
+  test('resolves no dependencies for non-existent path', () => {
+    const resolved = dependencyResolver.resolveRecursive('/non/existent/path');
+    expect(Array.from(resolved)).toHaveLength(0);
+  });
+
+  test('resolves dependencies for existing path', () => {
+    const resolved = dependencyResolver.resolveRecursive(
+      path.resolve(__dirname, '__fixtures__', 'recursive', 'a.js'),
+    );
+    expect(Array.from(resolved)).toEqual([
+      expect.stringContaining('b.js'),
+      expect.stringContaining('c1.js'),
+      expect.stringContaining('c2.js'),
+    ]);
+  });
+
+  test('resolves circular dependencies', () => {
+    const resolved = dependencyResolver.resolveRecursive(
+      path.resolve(__dirname, '__fixtures__', 'circular', 'a.js'),
+    );
+    expect(Array.from(resolved)).toEqual([
+      expect.stringContaining('b.js'),
+      expect.stringContaining('c.js'),
+    ]);
+  });
+});
+
 describe('resolveInverse', () => {
   test('resolves no inverse dependencies for empty paths set', () => {
     const paths = new Set();
     const resolved = dependencyResolver.resolveInverse(paths, filter);
-    expect(resolved.length).toEqual(0);
+    expect(resolved).toHaveLength(0);
   });
 
   test('resolves no inverse dependencies for set of non-existent paths', () => {
     const paths = new Set(['/non/existent/path', '/another/one']);
     const resolved = dependencyResolver.resolveInverse(paths, filter);
-    expect(resolved.length).toEqual(0);
+    expect(resolved).toHaveLength(0);
   });
 
   test('resolves inverse dependencies for existing path', () => {
diff --git a/packages/jest-resolve-dependencies/src/index.js b/packages/jest-resolve-dependencies/src/index.js
index bebb7a76e212..cd2752e79e0c 100644
--- a/packages/jest-resolve-dependencies/src/index.js
+++ b/packages/jest-resolve-dependencies/src/index.js
@@ -18,8 +18,10 @@ import type {SnapshotResolver} from 'types/SnapshotResolver';
 import {isSnapshotPath} from 'jest-snapshot';
 
 /**
- * DependencyResolver is used to resolve the direct dependencies of a module or
- * to retrieve a list of all transitive inverse dependencies.
+ * DependencyResolver is used
+ * to resolve the direct dependencies of a module (resolve) or
+ * to resolve the transitive (direct and indirect) dependencies of a module (resolveRecursive) or
+ * to retrieve a list of all transitive inverse dependencies (resolveInverse{,ModuleMap}).
  */
 class DependencyResolver {
   _hasteFS: HasteFS;
@@ -65,6 +67,21 @@ class DependencyResolver {
     }, []);
   }
 
+  resolveRecursive(rootFile: Path, options?: ResolveModuleConfig): Set<Path> {
+    const known = new Set();
+    const recurse = (file: Path) => {
+      if (known.has(file)) {
+        return;
+      }
+      if (file !== rootFile) {
+        known.add(file);
+      }
+      this.resolve(file, options).forEach(recurse);
+    };
+    recurse(rootFile);
+    return known;
+  }
+
   resolveInverseModuleMap(
     paths: Set<Path>,
     filter: (file: Path) => boolean,

From 22fee13502e860681939418bf1d23e4d4547777a Mon Sep 17 00:00:00 2001
From: Tim Seckinger <seckinger.tim@gmail.com>
Date: Mon, 31 Dec 2018 00:53:20 +0100
Subject: [PATCH 3/5] add DependencyResolver includeCoreModules option

---
 CHANGELOG.md                                  |  1 +
 .../src/__tests__/__fixtures__/core.test.js   | 10 ++++++
 .../src/__tests__/dependency_resolver.test.js | 34 +++++++++++++++++++
 .../jest-resolve-dependencies/src/index.js    |  4 ++-
 types/Resolve.js                              |  1 +
 5 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 packages/jest-resolve-dependencies/src/__tests__/__fixtures__/core.test.js

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7aca48592cc8..2f5e4392d959 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ### Features
 
 - `[jest-resolve-dependencies]` Add `DependencyResolver.resolveRecursive` ([#7553](https://github.com/facebook/jest/pull/7553))
+- `[jest-resolve-dependencies]` Add `DependencyResolver includeCoreModules` option ([#7553](https://github.com/facebook/jest/pull/7553))
 
 ### Fixes
 
diff --git a/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/core.test.js b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/core.test.js
new file mode 100644
index 000000000000..89d023cba71e
--- /dev/null
+++ b/packages/jest-resolve-dependencies/src/__tests__/__fixtures__/core.test.js
@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+'use strict';
+
+require('fs');
diff --git a/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js b/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js
index b8406f5e849d..6a5284ba474e 100644
--- a/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js
+++ b/packages/jest-resolve-dependencies/src/__tests__/dependency_resolver.test.js
@@ -64,6 +64,23 @@ describe('resolve', () => {
       expect.stringContaining(path.join('@myorg', 'pkg')),
     ]);
   });
+
+  describe('includeCoreModules', () => {
+    test('does not include core modules without the option', () => {
+      const resolved = dependencyResolver.resolve(
+        path.resolve(__dirname, '__fixtures__', 'core.test.js'),
+      );
+      expect(Array.from(resolved)).toEqual([]);
+    });
+
+    test('includes core modules with the option', () => {
+      const resolved = dependencyResolver.resolve(
+        path.resolve(__dirname, '__fixtures__', 'core.test.js'),
+        {includeCoreModules: true},
+      );
+      expect(Array.from(resolved)).toEqual(['fs']);
+    });
+  });
 });
 
 describe('resolveRecursive', () => {
@@ -92,6 +109,23 @@ describe('resolveRecursive', () => {
       expect.stringContaining('c.js'),
     ]);
   });
+
+  describe('includeCoreModules', () => {
+    test('does not include core modules without the option', () => {
+      const resolved = dependencyResolver.resolveRecursive(
+        path.resolve(__dirname, '__fixtures__', 'core.test.js'),
+      );
+      expect(Array.from(resolved)).toEqual([]);
+    });
+
+    test('includes core modules with the option', () => {
+      const resolved = dependencyResolver.resolveRecursive(
+        path.resolve(__dirname, '__fixtures__', 'core.test.js'),
+        {includeCoreModules: true},
+      );
+      expect(Array.from(resolved)).toEqual(['fs']);
+    });
+  });
 });
 
 describe('resolveInverse', () => {
diff --git a/packages/jest-resolve-dependencies/src/index.js b/packages/jest-resolve-dependencies/src/index.js
index cd2752e79e0c..78e207739d37 100644
--- a/packages/jest-resolve-dependencies/src/index.js
+++ b/packages/jest-resolve-dependencies/src/index.js
@@ -44,8 +44,10 @@ class DependencyResolver {
       return [];
     }
 
+    const includeCoreModules = options && options.includeCoreModules;
+
     return dependencies.reduce((acc, dependency) => {
-      if (this._resolver.isCoreModule(dependency)) {
+      if (!includeCoreModules && this._resolver.isCoreModule(dependency)) {
         return acc;
       }
       let resolvedDependency;
diff --git a/types/Resolve.js b/types/Resolve.js
index facd55e4fc56..fc778cb06269 100644
--- a/types/Resolve.js
+++ b/types/Resolve.js
@@ -13,6 +13,7 @@ import type {Path} from './Config';
 
 export type ResolveModuleConfig = {|
   skipNodeResolution?: boolean,
+  includeCoreModules?: boolean,
   paths?: Path[],
 |};
 

From 1ca41b52fd4745bd99b15dd605a69e7de311fecd Mon Sep 17 00:00:00 2001
From: Tim Seckinger <seckinger.tim@gmail.com>
Date: Wed, 26 Dec 2018 14:28:48 +0100
Subject: [PATCH 4/5] use file sizes of all dependencies in TestSequencer

---
 CHANGELOG.md                                  |  2 +
 packages/jest-cli/src/TestSequencer.js        | 65 +++++++++++++++-
 .../src/__tests__/test_sequencer.test.js      | 78 ++++++++++++++++---
 3 files changed, 132 insertions(+), 13 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2f5e4392d959..2d56697b33a6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,8 @@
 
 ### Performance
 
+- `[jest-cli]` Better test order heuristics on first run without cache ([#7553](https://github.com/facebook/jest/pull/7553))
+
 ## 24.1.0
 
 ### Features
diff --git a/packages/jest-cli/src/TestSequencer.js b/packages/jest-cli/src/TestSequencer.js
index b13c2e261d9e..f52e14fba715 100644
--- a/packages/jest-cli/src/TestSequencer.js
+++ b/packages/jest-cli/src/TestSequencer.js
@@ -10,10 +10,15 @@
 import type {AggregatedResult} from 'types/TestResult';
 import type {Context} from 'types/Context';
 import type {Test} from 'types/TestRunner';
+import type {Path} from 'types/Config';
+import type {Resolver} from 'types/Resolve';
+import type {HasteFS} from 'types/HasteMap';
 
 import fs from 'fs';
 // $FlowFixMe: Missing ESM export
 import {getCacheFilePath} from 'jest-haste-map';
+import DependencyResolver from 'jest-resolve-dependencies';
+import {buildSnapshotResolver} from 'jest-snapshot';
 
 const FAIL = 0;
 const SUCCESS = 1;
@@ -22,6 +27,17 @@ type Cache = {
   [key: string]: [0 | 1, number],
 };
 
+// If a test depends on one of these core modules,
+// we assume that the test may be slower because it is an "integration test"
+// that spawn child processes, accesses the file system, etc.
+// The weights are in bytes, just as the file sizes of regular modules.
+const coreModuleWeights = {
+  child_process: 1000000,
+  fs: 100000,
+  http: 10000,
+  https: 10000,
+};
+
 export default class TestSequencer {
   _cache: Map<Context, Cache>;
 
@@ -57,6 +73,46 @@ export default class TestSequencer {
     return cache;
   }
 
+  _fileSize(
+    path: Path,
+    sizes: Map<Path, number>,
+    resolver: Resolver,
+    hasteFS: HasteFS,
+  ): number {
+    const cachedSize = sizes.get(path);
+    if (cachedSize != null) {
+      return cachedSize;
+    }
+
+    const size =
+      (resolver.isCoreModule(path)
+        ? coreModuleWeights[path]
+        : hasteFS.getSize(path)) || 0;
+    sizes.set(path, size);
+    return size;
+  }
+
+  _fileSizeRecurseDependencies(test: Test, sizes: Map<Path, number>): number {
+    const {resolver, hasteFS, config} = test.context;
+
+    const dependencyResolver = new DependencyResolver(
+      resolver,
+      hasteFS,
+      buildSnapshotResolver(config),
+    );
+    const recursiveDependencies = dependencyResolver.resolveRecursive(
+      test.path,
+      {includeCoreModules: true},
+    );
+    const size =
+      Array.from(recursiveDependencies).reduce(
+        (sum, path) => sum + this._fileSize(path, sizes, resolver, hasteFS),
+        0,
+      ) + this._fileSize(test.path, sizes, resolver, hasteFS);
+
+    return size;
+  }
+
   // When running more tests than we have workers available, sort the tests
   // by size - big test files usually take longer to complete, so we run
   // them first in an effort to minimize worker idle time at the end of a
@@ -66,9 +122,7 @@ export default class TestSequencer {
   // subsequent runs we use that to run the slowest tests first, yielding the
   // fastest results.
   sort(tests: Array<Test>): Array<Test> {
-    const stats = {};
-    const fileSize = ({path, context: {hasteFS}}) =>
-      stats[path] || (stats[path] = hasteFS.getSize(path) || 0);
+    const sizes = new Map();
     const hasFailed = (cache, test) =>
       cache[test.path] && cache[test.path][0] === FAIL;
     const time = (cache, test) => cache[test.path] && cache[test.path][1];
@@ -88,7 +142,10 @@ export default class TestSequencer {
       } else if (testA.duration != null && testB.duration != null) {
         return testA.duration < testB.duration ? 1 : -1;
       } else {
-        return fileSize(testA) < fileSize(testB) ? 1 : -1;
+        return this._fileSizeRecurseDependencies(testA, sizes) <
+          this._fileSizeRecurseDependencies(testB, sizes)
+          ? 1
+          : -1;
       }
     });
   }
diff --git a/packages/jest-cli/src/__tests__/test_sequencer.test.js b/packages/jest-cli/src/__tests__/test_sequencer.test.js
index 2e0c8d00f0ea..0793e8344a58 100644
--- a/packages/jest-cli/src/__tests__/test_sequencer.test.js
+++ b/packages/jest-cli/src/__tests__/test_sequencer.test.js
@@ -12,11 +12,40 @@ jest.mock('fs');
 
 const fs = require('fs');
 const path = require('path');
+const mockResolveRecursive = jest.fn(
+  (path, options) =>
+    ({
+      '/test-a.js': ['/sut-a.js', '/test-util.js'],
+      '/test-ab.js': ['/sut-ab.js'],
+      '/test-b.js': ['/sut-b0.js'],
+      '/test-cp.js': ['child_process'],
+      '/test-e.js': ['/sut-e.js'],
+      '/test-fs.js': ['fs'],
+      '/test-http.js': ['http'],
+    }[path] || []),
+);
+afterEach(() => {
+  mockResolveRecursive.mockClear();
+});
+jest.mock(
+  'jest-resolve-dependencies',
+  () =>
+    class {
+      constructor() {
+        this.resolveRecursive = mockResolveRecursive;
+      }
+    },
+);
+
 const FAIL = 0;
 const SUCCESS = 1;
 
 let sequencer;
 
+const resolver = {
+  isCoreModule: path => !path.startsWith('/'),
+};
+
 const context = {
   config: {
     cache: true,
@@ -26,6 +55,7 @@ const context = {
   hasteFS: {
     getSize: path => path.length,
   },
+  resolver,
 };
 
 const secondContext = {
@@ -37,6 +67,7 @@ const secondContext = {
   hasteFS: {
     getSize: path => path.length,
   },
+  resolver,
 };
 
 const toTests = paths =>
@@ -54,11 +85,40 @@ beforeEach(() => {
   fs.writeFileSync = jest.fn();
 });
 
-test('sorts by file size if there is no timing information', () => {
-  expect(sequencer.sort(toTests(['/test-a.js', '/test-ab.js']))).toEqual([
+test('sorts by dependency file sizes if there is no timing information', () => {
+  expect(sequencer.sort(toTests(['/test-ab.js', '/test-a.js']))).toEqual([
+    {context, duration: undefined, path: '/test-a.js'},
+    {context, duration: undefined, path: '/test-ab.js'},
+  ]);
+  expect(mockResolveRecursive).toHaveBeenCalledWith(expect.any(String), {
+    includeCoreModules: true,
+  });
+});
+
+test('includes the test file itself during size calculation', () => {
+  expect(sequencer.sort(toTests(['/test-b.js', '/test-ab.js']))).toEqual([
     {context, duration: undefined, path: '/test-ab.js'},
+    {context, duration: undefined, path: '/test-b.js'},
+  ]);
+  expect(mockResolveRecursive).toHaveBeenCalledWith(expect.any(String), {
+    includeCoreModules: true,
+  });
+});
+
+test('prioritizes tests that depend on certain core modules', () => {
+  expect(
+    sequencer.sort(
+      toTests(['/test-a.js', '/test-cp.js', '/test-fs.js', '/test-http.js']),
+    ),
+  ).toEqual([
+    {context, duration: undefined, path: '/test-cp.js'},
+    {context, duration: undefined, path: '/test-fs.js'},
+    {context, duration: undefined, path: '/test-http.js'},
     {context, duration: undefined, path: '/test-a.js'},
   ]);
+  expect(mockResolveRecursive).toHaveBeenCalledWith(expect.any(String), {
+    includeCoreModules: true,
+  });
 });
 
 test('sorts based on timing information', () => {
@@ -95,14 +155,14 @@ test('sorts based on failures and timing information', () => {
   ]);
 });
 
-test('sorts based on failures, timing information and file size', () => {
+test('sorts based on failures, timing information and dependency file sizes', () => {
   fs.readFileSync = jest.fn(() =>
     JSON.stringify({
       '/test-a.js': [SUCCESS, 5],
       '/test-ab.js': [FAIL, 1],
-      '/test-c.js': [FAIL],
+      '/test-cd.js': [FAIL],
       '/test-d.js': [SUCCESS, 2],
-      '/test-efg.js': [FAIL],
+      '/test-e.js': [FAIL],
     }),
   );
   expect(
@@ -110,14 +170,14 @@ test('sorts based on failures, timing information and file size', () => {
       toTests([
         '/test-a.js',
         '/test-ab.js',
-        '/test-c.js',
+        '/test-cd.js',
         '/test-d.js',
-        '/test-efg.js',
+        '/test-e.js',
       ]),
     ),
   ).toEqual([
-    {context, duration: undefined, path: '/test-efg.js'},
-    {context, duration: undefined, path: '/test-c.js'},
+    {context, duration: undefined, path: '/test-e.js'},
+    {context, duration: undefined, path: '/test-cd.js'},
     {context, duration: 1, path: '/test-ab.js'},
     {context, duration: 5, path: '/test-a.js'},
     {context, duration: 2, path: '/test-d.js'},

From 2920417b78889b70d559e22546c7921ade138c41 Mon Sep 17 00:00:00 2001
From: Tim Seckinger <seckinger.tim@gmail.com>
Date: Wed, 26 Dec 2018 17:42:48 +0100
Subject: [PATCH 5/5] add test case for ordering to list-tests e2e test

---
 .../__snapshots__/listTests.test.js.snap          |  3 ++-
 e2e/__tests__/listTests.test.js                   | 10 ++++++++++
 e2e/list-tests/__tests__/other.test.js            |  3 +++
 e2e/list-tests/__tests__/with-dep.test.js         | 15 +++++++++++++++
 4 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 e2e/list-tests/__tests__/with-dep.test.js

diff --git a/e2e/__tests__/__snapshots__/listTests.test.js.snap b/e2e/__tests__/__snapshots__/listTests.test.js.snap
index 3c12f33eab07..9133d1e0efc4 100644
--- a/e2e/__tests__/__snapshots__/listTests.test.js.snap
+++ b/e2e/__tests__/__snapshots__/listTests.test.js.snap
@@ -3,6 +3,7 @@
 exports[`--listTests flag causes tests to be printed in different lines 1`] = `
 /MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/dummy.test.js
 /MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/other.test.js
+/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/with-dep.test.js
 `;
 
-exports[`--listTests flag causes tests to be printed out as JSON when using the --json flag 1`] = `["/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/dummy.test.js","/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/other.test.js"]`;
+exports[`--listTests flag causes tests to be printed out as JSON when using the --json flag 1`] = `["/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/dummy.test.js","/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/other.test.js","/MOCK_ABOLUTE_PATH/e2e/list-tests/__tests__/with-dep.test.js"]`;
diff --git a/e2e/__tests__/listTests.test.js b/e2e/__tests__/listTests.test.js
index f7c4ad6cb7af..52276a27330d 100644
--- a/e2e/__tests__/listTests.test.js
+++ b/e2e/__tests__/listTests.test.js
@@ -35,6 +35,16 @@ describe('--listTests flag', () => {
     ).toMatchSnapshot();
   });
 
+  it('prints tests in the execution order determined by their dependency sizes', () => {
+    const {status, stdout} = runJest('list-tests', ['--listTests']);
+    expect(status).toBe(0);
+    expect(normalizePaths(stdout).split('\n')).toEqual([
+      expect.stringContaining('/with-dep.test.js'),
+      expect.stringContaining('/other.test.js'),
+      expect.stringContaining('/dummy.test.js'),
+    ]);
+  });
+
   it('causes tests to be printed out as JSON when using the --json flag', () => {
     const {status, stdout} = runJest('list-tests', ['--listTests', '--json']);
 
diff --git a/e2e/list-tests/__tests__/other.test.js b/e2e/list-tests/__tests__/other.test.js
index cfc1ee266fb4..2607de475730 100644
--- a/e2e/list-tests/__tests__/other.test.js
+++ b/e2e/list-tests/__tests__/other.test.js
@@ -11,3 +11,6 @@ it("isn't actually run", () => {
   // (because it is only used for --listTests)
   expect(true).toBe(false);
 });
+
+// Because of this comment, other.test.js is slightly larger than dummy.test.js.
+// This matters for the order in which tests are sequenced.
diff --git a/e2e/list-tests/__tests__/with-dep.test.js b/e2e/list-tests/__tests__/with-dep.test.js
new file mode 100644
index 000000000000..15648e892ab6
--- /dev/null
+++ b/e2e/list-tests/__tests__/with-dep.test.js
@@ -0,0 +1,15 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+require('./dummy.test.js');
+
+it("isn't actually run", () => {
+  // (because it is only used for --listTests)
+  expect(true).toBe(false);
+});