compare versions fn

Signed-off-by: shmck <shawn.j.mckay@gmail.com>

Author: ShMcK

package-lock.json

@@ -39,6 +39,7 @@
     "@types/jest": "^25.2.1",
     "@types/jsdom": "^16.2.0",
     "@types/node": "^13.11.0",
+    "@types/semver": "^7.1.0",
     "@typescript-eslint/eslint-plugin": "^2.26.0",
     "@typescript-eslint/parser": "^2.26.0",
     "chokidar": "^3.3.0",
@@ -49,6 +50,7 @@
     "jest": "^25.2.7",
     "jsdom": "^16.2.2",
     "prettier": "^2.0.2",
+    "semver": "^7.2.2",
     "ts-jest": "^25.3.1",
     "typescript": "^3.8.3"
   },

package.json

@@ -1,8 +1,10 @@
+import * as TT from 'typings/tutorial'
+import { satisfies } from 'semver'
 import node from '../node'
 
 const semverRegex = /(?<=^v?|\sv?)(?:0|[1-9]\d*)\.(?:0|[1-9]\d*)\.(?:0|[1-9]\d*)(?:-(?:0|[1-9]\d*|[\da-z-]*[a-z-][\da-z-]*)(?:\.(?:0|[1-9]\d*|[\da-z-]*[a-z-][\da-z-]*))*)?(?:\+[\da-z-]+(?:\.[\da-z-]+)*)?(?=$|\s)/gi
 
-export const getVersion = async (name: string): Promise<string | null> => {
+export const version = async (name: string): Promise<string | null> => {
   const { stdout, stderr } = await node.exec(`${name} --version`)
   if (!stderr) {
     const match = stdout.match(semverRegex)
@@ -12,3 +14,24 @@ export const getVersion = async (name: string): Promise<string | null> => {
   }
   return null
 }
+
+export const compareVersions = async ({
+  name,
+  version: expectedVersion,
+  message,
+}: TT.TutorialDependency): Promise<boolean> => {
+  const currentVersion = await version(name)
+  if (!currentVersion) {
+    // use a custom error message
+    if (message) {
+      throw new Error(message)
+    }
+    throw new Error(`Process ${name} is required but not found. It may need to be installed`)
+  }
+  // see node-semver docs: https://github.com/npm/node-semver
+  const satisfied: boolean = satisfies(currentVersion, expectedVersion)
+  if (!satisfied) {
+    throw new Error(`Expected ${name} to have version ${expectedVersion}, but found version ${currentVersion}`)
+  }
+  return true
+}

src/services/dependencies/index.ts

@@ -62,4 +62,5 @@ export interface TutorialRepo {
 export interface TutorialDependency {
   name: string
   version: string
+  message?: string
 }