feat(package): Add .refresh() method to update internal state when ex…

…ternal changes have occurred

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

@@ -1,9 +1,11 @@
 "use strict";
 
+jest.mock("load-json-file");
 jest.mock("write-pkg");
 
 const os = require("os");
 const path = require("path");
+const loadJsonFile = require("load-json-file");
 const writePkg = require("write-pkg");
 
 // file under test
@@ -204,6 +206,21 @@ describe("Package", () => {
     });
   });
 
+  describe(".refresh()", () => {
+    it("reloads private state from disk", async () => {
+      loadJsonFile.mockImplementationOnce(() => Promise.resolve({ name: "ignored", mutated: true }));
+
+      const pkg = factory({ name: "refresh" });
+
+      await pkg.refresh();
+
+      // a package's name never changes
+      expect(pkg.name).toBe("refresh");
+      expect(pkg.get("mutated")).toBe(true);
+      expect(loadJsonFile).toHaveBeenLastCalledWith(pkg.manifestLocation);
+    });
+  });
+
   describe(".serialize()", () => {
     it("writes changes to disk", async () => {
       writePkg.mockImplementation(() => Promise.resolve());

core/package/index.js

@@ -2,6 +2,7 @@
 
 const npa = require("libnpm/parse-arg");
 const path = require("path");
+const loadJsonFile = require("load-json-file");
 const writePkg = require("write-pkg");
 
 // symbol used to "hide" internal state
@@ -136,6 +137,20 @@ class Package {
     return shallowCopy(this[PKG]);
   }
 
+  /**
+   * Refresh internal state from disk (e.g., changed by external lifecycles)
+   */
+  refresh() {
+    return loadJsonFile(this.manifestLocation).then(pkg => {
+      // overwrite configurable property
+      Object.defineProperty(this, PKG, {
+        value: pkg,
+      });
+
+      return this;
+    });
+  }
+
   /**
    * Write manifest changes to disk
    * @returns {Promise} resolves when write finished

core/package/package.json

@@ -31,6 +31,7 @@
   },
   "dependencies": {
     "libnpm": "^2.0.1",
+    "load-json-file": "^4.0.0",
     "write-pkg": "^3.1.0"
   }
 }