Update status does not have tests with (semantic) Drupal 8 versions

Update status XML samples for future core versions can be generated by doing the release process on git7staging. It would be best to have a list of versions that are needed for test coverage, so they can be done all at once. I started a draft list under Proposed resolution.

There is a chance that update status should have different messaging for 8.1.0 being available vs. 8.0.1, they will be different enough upgrades. And we should check the messaging when both are available as upgrades.

Contrib is sticking to 8.x-y.z until #1612910: [policy, no patch] Switch to Semantic Versioning for Drupal contrib extensions (modules, themes, etc) decides on something different.

I should say contrib is sticking to version numbers like 8.x-1.2.

Attached are update status XML files as if each release has been created.

Taking a first stab at this.

I didn't add semantic versioning tests for contrib modules/themes per #3-#6.

Thank you @Devin Carlson!

The existing patch looks good but doesn't contain any -alpha, -beta, or 9.x.x releases; those should probably be added per the issue summary.

I think any messaging/UI concerns would be for another issue.

Thanks for the review and extra info Cottser and Gábor!

Working on adding additional coverage per #9. Attaching a reroll of #8 to verify that it passes after all of the changes made over the last couple of weeks (will set back to needs work).

#11 is green, yay. Back to needs work per the comment.

An updated patch that adds coverage for -alpha, -beta and updating from Drupal 8.x.x-x to 9.0.0.

Interdiff between #11 and #13.

#13 looks really good to me, especially all the extra cases covered by the test*Available() tests. But, I'm wondering why the following tests:

+++ b/core/modules/update/src/Tests/UpdateCoreTest.php
@@ -98,82 +186,112 @@ function testDatestampMismatch() {
   function testModulePageRunCron() {
   function testModulePageUpToDate() {
   function testModulePageRegularUpdate() {
   function testModulePageSecurityUpdate() {
   function testLanguageModuleUpdate() {

all require

-    $this->setSystemInfo7_0();
+    foreach (array(0, 1) as $minor_version) {
+      foreach (array('-alpha1', '-beta1', '') as $extra_version) {
+        $this->setSystemInfo("8.$minor_version.0" . $extra_version);

Looks to me like they're testing stuff that's independent of starting version, so I don't see what we gain by iterating all the versions. Would it make sense for these tests to just test an 8.0.0 starting point?

Also, same question for UpdateUploadTest.

Addressing the feedback in #16.

Thanks!

Committed cac5f7a and pushed to 8.0.x. Thanks!