2.1 install moment

Author: ShMcK

test/packagejson.test.js

@@ -1,4 +1,4 @@
-const { getPackageJson } = require("./utils");
+const { getPackageJson, isModuleInstalled, doesNotThrow } = require("./utils");
 const assert = require("assert");
 
 describe("package.json", () => {
@@ -54,4 +54,21 @@ describe("package.json", () => {
       'should have a "version" value that is a string'
     );
   });
+  // 2.1
+  it('should have "dependencies"', () => {
+    assert.ok(json.dependencies, '"dependencies" is missing');
+    assert.equal(
+      typeof json.dependencies,
+      "object",
+      'should have a "dependencies" value that is an object'
+    );
+  });
+  it('should have installed "moment"', async () => {
+    assert.ok(
+      await doesNotThrow(
+        () => isModuleInstalled({ name: "moment", type: "dependency" }),
+        '"moment" not installed'
+      )
+    );
+  });
 });

test/utils.js

@@ -1,5 +1,5 @@
 const {
-  promises: { readFile }
+  promises: { readFile, readdir }
 } = require("fs");
 const { join } = require("path");
 
@@ -21,3 +21,66 @@ const getPackageJson = async () => {
 };
 
 exports.getPackageJson = getPackageJson;
+
+/**
+ * isModuleInstalled
+ * @param { name, type } params
+ * "name" - the name of the dependency
+ * "type" - "dependency", "devDependency", "peerDependency"
+ * @returns boolean
+ */
+const isModuleInstalled = async ({ name, type }) => {
+  // 1. load package.json file
+  const json = await getPackageJson();
+
+  // 2. verify package lists dependency by type
+  let installCommand;
+  let hasDependency;
+
+  switch (type) {
+    case "dependency":
+      installCommand = "--save";
+      hasDependency = !!json.dependencies && json.dependencies[name];
+      break;
+    case "devDependency":
+      installCommand = "--save-dev";
+      hasDependency = !!json.devDependencies && json.devDependencies[name];
+      break;
+    case "peerDependency":
+      throw new Error("Peer dependencies unsupported");
+    default:
+      throw new Error("Unsupported packaged type");
+  }
+
+  if (!hasDependency) {
+    throw new Error(`Run "npm install ${installCommand} ${name}"`);
+  }
+
+  // 3. verify node_module installed
+  const pathToNodeModule = join(process.cwd(), "node_modules", name);
+  const hasNodeModules = await readdir(pathToNodeModule).catch(() => {
+    throw new Error('Missing node_modules. Run "npm install"');
+  });
+  if (!hasNodeModules) {
+    throw new Error('Missing node_modules. Run "npm install"');
+  }
+
+  // 4. is installed
+  return true;
+};
+
+exports.isModuleInstalled = isModuleInstalled;
+
+// created because assert.doesNotThrow not working predictably with async fns
+const doesNotThrow = async fn => {
+  let result = true;
+  try {
+    await fn();
+  } catch (error) {
+    console.error(error);
+    result = false;
+  }
+  return result;
+};
+
+exports.doesNotThrow = doesNotThrow;