feat: allow using "next" version on supported version (#58)

This also allows using the action in https://github.com/mage-os/generate-mirror-repo-js where the test module is an external package installed with composer. In this case, no local path repo configuration is needed.

Co-authored-by: Vinai Kopp <Vinai@users.noreply.github.com>

supported-version/src/nightly/get-next-version.ts

@@ -0,0 +1,44 @@
+import { GithubActionsMatrix } from "../matrix/matrix-type";
+
+export type Repository = "https://upstream-mirror.mage-os.org" | "https://repo.magento.com";
+
+/**
+ * A placeholder value use to refer to the next version of Magento.
+ * This value is just a placeholder, there is no "next" version (as of authoring).
+ */
+export const nextVersionPlaceHolder = "magento/project-community-edition:next";
+
+/**
+ * Get the next version of Magento, as determined by the repository.
+ */
+export const getNextVersion = (repository: Repository, date: Date) => {
+    switch(repository){
+        case "https://upstream-mirror.mage-os.org":
+            // See: https://github.com/mage-os/generate-mirror-repo-js/blob/bbbdf1708ea0bf8fc845aad8240d00f37632b4a7/src/release-branch-build-tools.js#L71
+            return "@alpha";
+        default:
+            return "";
+    }
+}
+
+
+export const replaceNextPlaceHolderWithVersion = (packageName: string, nextVersion: string) => {
+    return packageName.replace(/(?!:)next$/, nextVersion);
+}
+
+export const computeNextPackage = (packageName: string, repository: Repository, date: Date): string => {
+    return replaceNextPlaceHolderWithVersion(packageName, getNextVersion(repository, date));
+}
+
+export const amendMatrixForNext = (matrix: GithubActionsMatrix, repository: Repository = "https://upstream-mirror.mage-os.org", date: Date = new Date()): GithubActionsMatrix => {
+    matrix.magento = matrix.magento.map((item) => item === nextVersionPlaceHolder ? computeNextPackage(nextVersionPlaceHolder, repository, date) : item);
+    matrix.include = matrix.include.map((item) => {
+        return item.magento === nextVersionPlaceHolder 
+            ? {
+                ...item,
+                magento: computeNextPackage(nextVersionPlaceHolder, repository, date),
+            }
+            : item;
+    });
+    return matrix;
+}