1.1 install express

Author: ShMcK

src/server.js

@@ -0,0 +1,9 @@
+const express = require("express");
+
+const app = express();
+
+const server = app.listen(process.env.PORT || 3000);
+
+// -- DO NOT EDIT BELOW THIS LINE
+
+module.exports = server;

test/dependency.test.js

@@ -0,0 +1,17 @@
+const assert = require("assert");
+
+const { doesNotThrow, isModuleInstalled } = require("./utils");
+
+describe("package.json", () => {
+  // 1.1.
+  it('should have "express" installed', async () => {
+    assert.ok(
+      await doesNotThrow(() =>
+        isModuleInstalled({
+          name: "express",
+          type: "dependency"
+        })
+      )
+    );
+  });
+});

test/utils.js

@@ -0,0 +1,113 @@
+const {
+  promises: { readFile, readdir }
+} = require("fs");
+const { join } = require("path");
+
+const getPackageJson = async (dir = process.cwd()) => {
+  // load package.json file
+  const pathToPackageJson = join(dir, "package.json");
+  const packageJson = await readFile(pathToPackageJson, "utf8").catch(
+    console.error
+  );
+  if (!packageJson) {
+    throw new Error("Missing root package.json");
+  }
+  // parse as JSON
+  const json = JSON.parse(packageJson);
+  if (!json) {
+    throw new Error("The package.json content looks invalid");
+  }
+  return json;
+};
+
+exports.getPackageJson = getPackageJson;
+
+const versionMatch = (current, expected) => {
+  let currentSemver = current;
+  if (["~", "^"].includes(current[0])) {
+    currentSemver = current.substring(1);
+  }
+  return currentSemver === expected;
+};
+
+/**
+ * isModuleInstalled
+ * @param { name, type } params
+ * "name" - the name of the dependency
+ * "type" - "dependency", "devDependency", "peerDependency"
+ * @returns boolean
+ */
+const isModuleInstalled = async ({ name, type, version }) => {
+  // 1. load package.json file
+  const json = await getPackageJson();
+
+  // 2. verify package lists dependency by type
+  let installCommand;
+  let hasDependency;
+  let currentVersion;
+
+  switch (type) {
+    case "dependency":
+      installCommand = "--save";
+      hasDependency = !!json.dependencies && json.dependencies[name];
+      currentVersion = json.dependencies[name];
+      break;
+    case "devDependency":
+      installCommand = "--save-dev";
+      hasDependency = !!json.devDependencies && json.devDependencies[name];
+      currentVersion = 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. if version, check dependency version
+  if (version && !versionMatch(currentVersion, version)) {
+    throw new Error(
+      `Dependency ${name} version ${currentVersion} does not match expected ${version}`
+    );
+  }
+
+  // 4. 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"');
+  }
+
+  // 5. if version, has installed node_module version
+  if (version) {
+    const nodeModulePackageJson = await getPackageJson(pathToNodeModule);
+    if (!versionMatch(nodeModulePackageJson.version, version)) {
+      throw new Error(
+        `Dependency ${name} version ${version} is not yet installed. Run "npm install"`
+      );
+    }
+  }
+
+  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;