feat: Add check-package-json CLI command

When using `@guardian/cdk` the version of `aws-cdk` libraries in your `package.json` must exactly match the version `@guardian/cdk` uses.

This command allows you to provide a `package.json` file to check if the versions of `aws-cdk` libraries match what `@guardian/cdk` uses.

jest.setup.js

@@ -1 +1,2 @@
 jest.mock("./src/constants/tracking-tag");
+jest.mock("./src/constants/library-info");

src/bin/commands/check-package-json.test.ts

@@ -0,0 +1,72 @@
+import { promises } from "fs";
+import { checkPackageJson } from "./check-package-json";
+
+describe("checkPackageJson", () => {
+  const mockPackageJson = (content: unknown) => {
+    jest.spyOn(promises, "access").mockReturnValue(Promise.resolve());
+    jest.spyOn(promises, "readFile").mockReturnValue(Promise.resolve(JSON.stringify(content)));
+  };
+
+  afterEach(() => {
+    jest.resetAllMocks();
+  });
+
+  it("should succeed when the versions match exactly", async () => {
+    mockPackageJson({
+      dependencies: {
+        "aws-cdk": "0.0.1",
+        "@aws-cdk/aws-ec2": "0.0.1",
+      },
+    });
+
+    const actual = await checkPackageJson("/tmp");
+
+    const expected = {
+      file: "/tmp/package.json",
+      incorrectDependencies: {},
+      incorrectDevDependencies: {},
+      versionExpected: "0.0.1",
+    };
+
+    expect(actual).toStrictEqual(expected);
+  });
+
+  it("should fail when the versions do not match exactly", async () => {
+    mockPackageJson({
+      dependencies: {
+        "aws-cdk": "^0.0.1",
+        "@aws-cdk/aws-ec2": "0.0.1",
+      },
+      devDependencies: {
+        "@aws-cdk/aws-iam": "0.0.2",
+      },
+    });
+
+    try {
+      await checkPackageJson("/tmp");
+    } catch (actual) {
+      const expected = {
+        file: "/tmp/package.json",
+        incorrectDependencies: {
+          "aws-cdk": "^0.0.1",
+        },
+        incorrectDevDependencies: {
+          "@aws-cdk/aws-iam": "0.0.2",
+        },
+        versionExpected: "0.0.1",
+      };
+      expect(actual).toStrictEqual(expected);
+    }
+  });
+
+  it("should fail when the package.json file does not exist", async () => {
+    jest.spyOn(promises, "access").mockReturnValue(Promise.reject());
+
+    try {
+      await checkPackageJson("/tmp");
+    } catch (actual) {
+      const expected = "File not found: /tmp/package.json";
+      expect(actual).toBe(expected);
+    }
+  });
+});

src/bin/commands/check-package-json.ts

@@ -0,0 +1,39 @@
+import { access, readFile } from "fs/promises";
+import path from "path";
+import type { PackageJson } from "read-pkg-up";
+import { LibraryInfo } from "../../constants/library-info";
+import type { CliCommandResponse } from "../../types/command";
+import { getAwsCdkDependencies } from "../../utils/package-json";
+
+const filterVersionMismatch = (deps: Record<string, string>) =>
+  Object.fromEntries(Object.entries(deps).filter(([, version]) => version !== LibraryInfo.AWS_CDK_VERSION));
+
+export const checkPackageJson = async (directory: string): CliCommandResponse => {
+  const packageJsonPath = path.join(directory, "package.json");
+
+  try {
+    await access(packageJsonPath);
+  } catch (error) {
+    return Promise.reject(`File not found: ${packageJsonPath}`);
+  }
+
+  const fileContent = await readFile(packageJsonPath, { encoding: "utf8" });
+  const packageJson = JSON.parse(fileContent) as PackageJson;
+
+  const { dependencies, devDependencies } = getAwsCdkDependencies(packageJson);
+
+  const depsMismatch = filterVersionMismatch(dependencies);
+  const devDepsMismatch = filterVersionMismatch(devDependencies);
+  const totalMismatch = Object.keys(depsMismatch).length + Object.keys(devDepsMismatch).length;
+
+  const isOk = totalMismatch === 0;
+
+  const response = {
+    file: packageJsonPath,
+    versionExpected: LibraryInfo.AWS_CDK_VERSION,
+    incorrectDependencies: depsMismatch,
+    incorrectDevDependencies: devDepsMismatch,
+  };
+
+  return isOk ? Promise.resolve(response) : Promise.reject(response);
+};

src/bin/index.ts

@@ -6,10 +6,12 @@ import type { CliCommandResponse } from "../types/command";
 import { awsCredentialProviderChain } from "./aws-credential-provider";
 import { accountReadinessCommand } from "./commands/account-readiness";
 import { awsCdkVersionCommand } from "./commands/aws-cdk-version";
+import { checkPackageJson } from "./commands/check-package-json";
 
 const Commands = {
   AwsCdkVersion: "aws-cdk-version",
   AccountReadiness: "account-readiness",
+  CheckPackageJson: "check-package-json",
 };
 
 const parseCommandLineArguments = () => {
@@ -26,6 +28,14 @@ const parseCommandLineArguments = () => {
       .option("region", { type: "string", description: "AWS region", default: "eu-west-1" })
       .command(Commands.AwsCdkVersion, "Print the version of @aws-cdk libraries being used")
       .command(Commands.AccountReadiness, "Perform checks on an AWS account to see if it is GuCDK ready")
+      .command(Commands.CheckPackageJson, "Check a package.json file for compatibility with GuCDK", (yargs) =>
+        yargs.option("directory", {
+          type: "string",
+          description: "The location of the package.json file to check",
+          default: process.cwd(),
+          defaultDescription: "The current working directory",
+        })
+      )
       .version(`${LibraryInfo.VERSION} (using @aws-cdk ${LibraryInfo.AWS_CDK_VERSION})`)
       .demandCommand(1, "") // just print help
       .help()
@@ -42,6 +52,10 @@ parseCommandLineArguments()
         return awsCdkVersionCommand();
       case Commands.AccountReadiness:
         return accountReadinessCommand({ credentialProvider: awsCredentialProviderChain(profile), region });
+      case Commands.CheckPackageJson: {
+        const { directory } = argv;
+        return checkPackageJson(directory);
+      }
       default:
         throw new Error(`Unknown command: ${command}`);
     }

src/constants/__mocks__/library-info.ts

@@ -0,0 +1,10 @@
+const mockAwsCdkVersion = "0.0.1";
+
+export const LibraryInfo = {
+  VERSION: "1.0.0",
+  AWS_CDK_VERSION: mockAwsCdkVersion,
+  AWS_CDK_VERSIONS: {
+    "aws-cdk": mockAwsCdkVersion,
+    "@aws-cdk/core": mockAwsCdkVersion,
+  },
+};