Helpers fail to resolve from .hbs.js file with embroider 2.x and static helpers

[bendemboski]

Broken off of #1293

When building with embroider 2.x and static helpers, <BasicDropdown> fails to render because it fails to resolve any of its helpers (starting with ensure-safe-component). It looks like a template compilation problem, perhaps specific to files that end up with the .hbs.js extension.

this repo demonstrates the issue, and its README describes what I've found through my investigation.

[ef4]

Thanks for the reproduction, I see the bug. When @embroider/compat is detecting what babel plugins are present in a v1 addon, it needs to remove any template compiler that's already present so that we can use our own. But it's failing to detect the template compiler installed by the newest ember-cli-htmlbars on new-enough ember versions.

This will be the fix, I just need to look through our test suite to see why this wasn't already being covered.

diff --git a/packages/compat/src/detect-babel-plugins.ts b/packages/compat/src/detect-babel-plugins.ts
index dbcd663e..1e65a7ba 100644
--- a/packages/compat/src/detect-babel-plugins.ts
+++ b/packages/compat/src/detect-babel-plugins.ts
@@ -76,4 +76,5 @@ const htmlbarPathMatches = [
   ['ember-cli-htmlbars', 'lib', 'require-from-worker.js'].join(sep),
   ['ember-cli-htmlbars', 'index'].join(sep),
   ['ember-cli-htmlbars', 'lib', 'require-from-worker'].join(sep),
+  ['babel-plugin-ember-template-compilation', 'src', 'node-main.js'].join(sep),
 ];

[ef4]

I figured out why the tests don't notice this -- it's because this case only happens if some other babel plugin is preventing ember-cli-babel from parallelizing.