ci: Add sloppy /test command (#33558)

Adds support for a `/test` command, without breaking the existing
`/ok-to-test` habits.

This is a _sloppy_ version of `/ok-to-test`. Turns out humans are
sloppy. So let's embrace the human. 🤯

Example incantation:
```
/test sanity workflow
```

The sloppy parser at work:

![shot-2024-05-18-03-40-30](https://github.com/appsmithorg/appsmith/assets/120119/0d495e88-a242-4f2b-a73c-bcf6e58cc9ad)

Of course, if a PR body contains `/ok-to-test`, that takes precedence,
and any `/test` is ignored.

We're also moving the logic of parsing the tags to a separate Javascript
file. It's still not in a form that's easily testable, perhaps, but I
hope this is a start for us to get to a "unit-tested CI". ❤️

---------

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

.github/workflows/pr-automation.yml

@@ -34,16 +34,16 @@ jobs:
                 exit 1
               fi
 
-      # Reads the PR description to retrieve /ok-to-test slash command
+      # Reads the PR description to retrieve the /ok-to-test or, if that's absent, the /test command
       - name: Get tags
+        uses: actions/github-script@v7
         id: getTags
         env:
-          PR_BODY: ${{ github.event.pull_request.body }}
-        run: |
-          REGEX='/ok-to-test tags="([^"]*)"';
-          if [[ $PR_BODY =~ $REGEX ]]; then
-            echo "tags=${BASH_REMATCH[1]}" >> $GITHUB_OUTPUT
-          fi
+          NODE_PATH: "${{ github.workspace }}/.github/workflows/scripts"
+        with:
+          script: |
+            const testTagParser = require("test-tag-parser.js")
+            core.setOutput("tags", testTagParser.parseTags({core, context}))
 
       # Parses the retrieved /ok-to-test slash command to retrieve tags
       - name: Parse tags

.github/workflows/scripts/test-tag-parser.js

@@ -0,0 +1,47 @@
+function parseTags({core, context}) {
+  const body = context.payload.pull_request.body;
+
+  // "/ok-to-test" matcher. Takes precedence over the "/test" matcher.
+  const strictMatch = body.match(/\/ok-to-test tags="(.+?)"/)?.[1];
+  if (strictMatch) {
+    return strictMatch;
+  }
+
+  // "/test" matcher.
+  const allTags = require(process.env.GITHUB_WORKSPACE + "/app/client/cypress/tags.js").Tag;
+  const config = body.match(/^\/test\s+(.*)$/m)?.[1] ?? "";
+  const concreteTags = [];
+
+  for (const [rawTag] of config.matchAll(/\w+/g)) {
+    console.log("Given: '" + rawTag + "'");
+
+    // See if there is exact case-insensitive match.
+    const exactTagMatch = allTags.find(t => t.toLowerCase() === "@tag." + rawTag);
+    if (exactTagMatch) {
+      console.log("\tMatch found:", exactTagMatch);
+      concreteTags.push(exactTagMatch);
+      continue;
+    }
+
+    // See if there is a singular/plural match (very rudimentary language skills).
+    const countedMatch = allTags.find(t => t.toLowerCase().replace(/s$/, "") === "@tag." + rawTag.replace(/s$/, ""));
+    if (countedMatch) {
+      console.log("\tMatch found:", countedMatch);
+      concreteTags.push(countedMatch);
+      continue;
+    }
+
+    // More smart matchers?
+
+    // No match, fail.
+    core.setFailed("\tNo match found for tag:", rawTag);
+
+    // We still process the rest, so we report all invalid tags in the input in a single run.
+  }
+
+  return concreteTags.join(", ");
+}
+
+module.exports = {
+  parseTags,
+}