feat: Support optionalDependencies

Fixes #121

commands/bootstrap/index.js

@@ -287,7 +287,12 @@ class BootstrapCommand extends Command {
     );
 
     // collect root dependency versions
-    const mergedRootDeps = Object.assign({}, rootPkg.devDependencies, rootPkg.dependencies);
+    const mergedRootDeps = Object.assign(
+      {},
+      rootPkg.optionalDependencies,
+      rootPkg.devDependencies,
+      rootPkg.dependencies
+    );
     const rootExternalVersions = new Map(
       Object.keys(mergedRootDeps).map(externalName => [externalName, mergedRootDeps[externalName]])
     );

commands/publish/__tests__/__fixtures__/normal/packages/package-5/package.json

@@ -3,6 +3,9 @@
   "dependencies": {
     "package-1": "^1.0.0"
   },
+  "optionalDependencies": {
+    "package-3": "^1.0.0"
+  },
   "private": true,
   "version": "1.0.0"
 }

commands/publish/__tests__/publish-command.test.js

@@ -139,6 +139,9 @@ describe("PublishCommand", () => {
       expect(updatedPackageJSON("package-5").dependencies).toMatchObject({
         "package-1": "^1.0.1",
       });
+      expect(updatedPackageJSON("package-5").optionalDependencies).toMatchObject({
+        "package-3": "^1.0.1",
+      });
 
       expect(gitAddedFiles(testDir)).toMatchSnapshot("git added files");
       expect(gitCommitMessage()).toEqual("v1.0.1");

core/package-graph/index.js

@@ -66,7 +66,12 @@ class PackageGraph extends Map {
       const graphDependencies =
         graphType === "dependencies"
           ? Object.assign({}, currentNode.pkg.dependencies)
-          : Object.assign({}, currentNode.pkg.devDependencies, currentNode.pkg.dependencies);
+          : Object.assign(
+              {},
+              currentNode.pkg.optionalDependencies,
+              currentNode.pkg.devDependencies,
+              currentNode.pkg.dependencies
+            );
 
       Object.keys(graphDependencies).forEach(depName => {
         const depNode = this.get(depName);

core/package/__tests__/core-package.test.js

@@ -96,6 +96,15 @@ describe("Package", () => {
     });
   });
 
+  describe("get .optionalDependencies", () => {
+    it("should return the optionalDependencies", () => {
+      const pkg = factory({
+        optionalDependencies: { "my-optional-dependency": "^1.0.0" },
+      });
+      expect(pkg.optionalDependencies).toEqual({ "my-optional-dependency": "^1.0.0" });
+    });
+  });
+
   describe("get .peerDependencies", () => {
     it("should return the peerDependencies", () => {
       const pkg = factory({

core/package/index.js

@@ -65,6 +65,11 @@ class Package {
           return pkg.devDependencies;
         },
       },
+      optionalDependencies: {
+        get() {
+          return pkg.optionalDependencies;
+        },
+      },
       peerDependencies: {
         get() {
           return pkg.peerDependencies;
@@ -106,7 +111,12 @@ class Package {
     // first, try runtime dependencies
     let depCollection = this.json.dependencies;
 
-    // fall back to devDependencies (it will always be one of these two)
+    // try optionalDependencies if that didn't work
+    if (!depCollection || !depCollection[depName]) {
+      depCollection = this.json.optionalDependencies;
+    }
+
+    // fall back to devDependencies
     if (!depCollection || !depCollection[depName]) {
       depCollection = this.json.devDependencies;
     }

integration/__fixtures__/lerna-bootstrap/package-1/package.json

@@ -8,5 +8,8 @@
   },
   "dependencies": {
     "pify": "^2.0.0"
+  },
+  "optionalDependencies": {
+    "tiny-tarball": "^1.0.0"
   }
 }

integration/__snapshots__/lerna-publish.test.js.snap

@@ -411,6 +411,9 @@ Array [
       package-1: ^1.0.1,
     },
     name: package-5,
+    optionalDependencies: Object {
+      package-3: ^1.0.1,
+    },
     private: true,
     version: 1.0.1,
   },

integration/lerna-bootstrap.test.js

@@ -25,7 +25,13 @@ describe("lerna bootstrap", () => {
     expect(lock1).toMatchObject({
       name: "@integration/package-1",
       version: "1.0.0",
-      dependencies: { pify: expect.any(Object) },
+      dependencies: {
+        pify: expect.any(Object),
+        "tiny-tarball": {
+          version: "1.0.0",
+          optional: true,
+        },
+      },
     });
     expect(lock2).toMatchObject({
       name: "@integration/package-2",
@@ -65,8 +71,15 @@ describe("lerna bootstrap", () => {
     expect(rootLock).toMatchObject({
       name: "integration",
       version: "0.0.0",
-      dependencies: { pify: expect.any(Object) },
+      dependencies: {
+        pify: expect.any(Object),
+        "tiny-tarball": {
+          version: "1.0.0",
+          // root hoist does not preserve optional
+        },
+      },
     });
+    expect(rootLock).not.toHaveProperty("dependencies.tiny-tarball.optional");
   });
 
   test("--npm-client yarn", async () => {