[CLEANUP] Fix missing ApplicationInstance in Router tests

[crazylogic03]

This PR removes a workaround in packages/@ember/routing/router.ts that allowed ApplicationInstance to be missing in tests. This occurred because RouterNonApplicationTestCase in packages/internal-test-helpers did not register an application instance.

I have updated the test case to register a mock ApplicationInstance, allowing the router to enforce strict dependency checks and removing the TODO(SAFETY) comment.

This ensures better type safety and correctness in the router's dependencies.

[github-actions]

Estimated Asset Sizes

Diff

--- main/out.txt	2026-02-16 14:34:00.000000000 +0000
+++ pr/./pr-22088232688/out.txt	2026-02-17 06:25:12.000000000 +0000
@@ -1,13 +1,13 @@
 ╔═══════╤═══════════╤═══════════╗
 ║       │ Min       │ Gzip      ║
 ╟───────┼───────────┼───────────╢
-║ Total │ 352.02 KB │ 203.83 KB ║
+║ Total │ 351.99 KB │ 203.84 KB ║
 ╚═══════╧═══════════╧═══════════╝
 
 ╔══════════════════════╤═══════════╤═══════════╗
 ║ @ember/*             │ Min       │ Gzip      ║
 ╟──────────────────────┼───────────┼───────────╢
-║ Total                │ 313.42 KB │ 181.89 KB ║
+║ Total                │ 313.39 KB │ 181.91 KB ║
 ╟──────────────────────┼───────────┼───────────╢
 ║ -internals           │ 36.65 KB  │ 26.22 KB  ║
 ║ application          │ 13.23 KB  │ 8.05 KB   ║
@@ -25,7 +25,7 @@
 ║ object               │ 35.94 KB  │ 22.16 KB  ║
 ║ owner                │ 159 B     │ 178 B     ║
 ║ renderer             │ 630 B     │ 487 B     ║
-║ routing              │ 59.33 KB  │ 34.1 KB   ║
+║ routing              │ 59.3 KB   │ 34.12 KB  ║
 ║ runloop              │ 2.36 KB   │ 1.5 KB    ║
 ║ service              │ 1 KB      │ 845 B     ║
 ║ template             │ 654 B     │ 541 B     ║

Details

This PR

main

╔═══════╤═══════════╤═══════════╗ ║ │ Min │ Gzip ║ ╟───────┼───────────┼───────────╢ ║ Total │ 351.99 KB │ 203.84 KB ║ ╚═══════╧═══════════╧═══════════╝ ╔══════════════════════╤═══════════╤═══════════╗ ║ @ember/* │ Min │ Gzip ║ ╟──────────────────────┼───────────┼───────────╢ ║ Total │ 313.39 KB │ 181.91 KB ║ ╟──────────────────────┼───────────┼───────────╢ ║ -internals │ 36.65 KB │ 26.22 KB ║ ║ application │ 13.23 KB │ 8.05 KB ║ ║ array │ 13.01 KB │ 7.46 KB ║ ║ canary-features │ 304 B │ 389 B ║ ║ component │ 2.05 KB │ 1.64 KB ║ ║ controller │ 1.96 KB │ 1.41 KB ║ ║ debug │ 11.69 KB │ 8.12 KB ║ ║ deprecated-features │ 31 B │ 77 B ║ ║ destroyable │ 561 B │ 383 B ║ ║ enumerable │ 259 B │ 387 B ║ ║ helper │ 1.08 KB │ 811 B ║ ║ instrumentation │ 2.43 KB │ 1.79 KB ║ ║ modifier │ 1.22 KB │ 965 B ║ ║ object │ 35.94 KB │ 22.16 KB ║ ║ owner │ 159 B │ 178 B ║ ║ renderer │ 630 B │ 487 B ║ ║ routing │ 59.3 KB │ 34.12 KB ║ ║ runloop │ 2.36 KB │ 1.5 KB ║ ║ service │ 1 KB │ 845 B ║ ║ template │ 654 B │ 541 B ║ ║ template-compilation │ 429 B │ 366 B ║ ║ template-compiler │ 123.08 KB │ 59.45 KB ║ ║ template-factory │ 370 B │ 374 B ║ ║ test │ 923 B │ 627 B ║ ║ utils │ 4.11 KB │ 3.6 KB ║ ║ version │ 55 B │ 131 B ║ ╚══════════════════════╧═══════════╧═══════════╝ ╔═════════════════╤══════════╤══════════╗ ║ @glimmer/* │ Min │ Gzip ║ ╟─────────────────┼──────────┼──────────╢ ║ Total │ 38.6 KB │ 21.94 KB ║ ╟─────────────────┼──────────┼──────────╢ ║ destroyable │ 2.77 KB │ 1.39 KB ║ ║ encoder │ 81 B │ 171 B ║ ║ env │ 38 B │ 87 B ║ ║ global-context │ 886 B │ 545 B ║ ║ manager │ 977 B │ 608 B ║ ║ node │ 175 B │ 260 B ║ ║ opcode-compiler │ 1.11 KB │ 894 B ║ ║ owner │ 159 B │ 202 B ║ ║ program │ 252 B │ 301 B ║ ║ reference │ 548 B │ 531 B ║ ║ runtime │ 10.32 KB │ 5.32 KB ║ ║ tracking │ 1.34 KB │ 1.16 KB ║ ║ util │ 1.94 KB │ 1.68 KB ║ ║ validator │ 15.75 KB │ 6.96 KB ║ ║ vm │ 495 B │ 569 B ║ ║ wire-format │ 1.84 KB │ 1.35 KB ║ ╚═════════════════╧══════════╧══════════╝

╔═══════╤═══════════╤═══════════╗ ║ │ Min │ Gzip ║ ╟───────┼───────────┼───────────╢ ║ Total │ 352.02 KB │ 203.83 KB ║ ╚═══════╧═══════════╧═══════════╝ ╔══════════════════════╤═══════════╤═══════════╗ ║ @ember/* │ Min │ Gzip ║ ╟──────────────────────┼───────────┼───────────╢ ║ Total │ 313.42 KB │ 181.89 KB ║ ╟──────────────────────┼───────────┼───────────╢ ║ -internals │ 36.65 KB │ 26.22 KB ║ ║ application │ 13.23 KB │ 8.05 KB ║ ║ array │ 13.01 KB │ 7.46 KB ║ ║ canary-features │ 304 B │ 389 B ║ ║ component │ 2.05 KB │ 1.64 KB ║ ║ controller │ 1.96 KB │ 1.41 KB ║ ║ debug │ 11.69 KB │ 8.12 KB ║ ║ deprecated-features │ 31 B │ 77 B ║ ║ destroyable │ 561 B │ 383 B ║ ║ enumerable │ 259 B │ 387 B ║ ║ helper │ 1.08 KB │ 811 B ║ ║ instrumentation │ 2.43 KB │ 1.79 KB ║ ║ modifier │ 1.22 KB │ 965 B ║ ║ object │ 35.94 KB │ 22.16 KB ║ ║ owner │ 159 B │ 178 B ║ ║ renderer │ 630 B │ 487 B ║ ║ routing │ 59.33 KB │ 34.1 KB ║ ║ runloop │ 2.36 KB │ 1.5 KB ║ ║ service │ 1 KB │ 845 B ║ ║ template │ 654 B │ 541 B ║ ║ template-compilation │ 429 B │ 366 B ║ ║ template-compiler │ 123.08 KB │ 59.45 KB ║ ║ template-factory │ 370 B │ 374 B ║ ║ test │ 923 B │ 627 B ║ ║ utils │ 4.11 KB │ 3.6 KB ║ ║ version │ 55 B │ 131 B ║ ╚══════════════════════╧═══════════╧═══════════╝ ╔═════════════════╤══════════╤══════════╗ ║ @glimmer/* │ Min │ Gzip ║ ╟─────────────────┼──────────┼──────────╢ ║ Total │ 38.6 KB │ 21.94 KB ║ ╟─────────────────┼──────────┼──────────╢ ║ destroyable │ 2.77 KB │ 1.39 KB ║ ║ encoder │ 81 B │ 171 B ║ ║ env │ 38 B │ 87 B ║ ║ global-context │ 886 B │ 545 B ║ ║ manager │ 977 B │ 608 B ║ ║ node │ 175 B │ 260 B ║ ║ opcode-compiler │ 1.11 KB │ 894 B ║ ║ owner │ 159 B │ 202 B ║ ║ program │ 252 B │ 301 B ║ ║ reference │ 548 B │ 531 B ║ ║ runtime │ 10.32 KB │ 5.32 KB ║ ║ tracking │ 1.34 KB │ 1.16 KB ║ ║ util │ 1.94 KB │ 1.68 KB ║ ║ validator │ 15.75 KB │ 6.96 KB ║ ║ vm │ 495 B │ 569 B ║ ║ wire-format │ 1.84 KB │ 1.35 KB ║ ╚═════════════════╧══════════╧══════════╝

[crazylogic03]

@NullVoxPopuli Please Have a Review On this PR and Let me Know if this requires any Update or changes

[NullVoxPopuli]

What error were you running in to that prompted looking in to this?

[crazylogic03]

@NullVoxPopuli I wasn't encountering a specific error in an application. I was looking through the codebase for cleanup opportunities and found the TODO(SAFETY) comment in

packages/@ember/routing/router.ts.
The comment explicitly flagged that Router Service - non application test was running without a correctly set

ApplicationInstance:
// TODO(SAFETY): At least one test runs without this set correctly. At a later time, update the test to configure this correctly.I addressed this by updating RouterNonApplicationTestCase to register a mock ApplicationInstance, which allowed me to remove the workaround and enforce the presence of the instance in
router.ts, improving the safety of the code.

[NullVoxPopuli]

Excellent! That certainly is helpful and i appreciate the effort!

To ensure there is no regression in the future, could you add a test that fails before this change and passes after? (Or, if you remove the register do a bunch of tests fail? This would satisfy regression prevention as well)

It's already a good signal that the whole test suite is currently passing already.

[crazylogic03]

@NullVoxPopuli i verified this locally. The changes to RouterNonApplicationTestCase
effectively serve as the regression test.
To confirm, I temporarily reverted the registration of -application-instance:main in the test case, and the test failed immediately with the expected assertion error: Assertion Failed: [BUG] unexpectedly missing -application-instance:main
This confirms that the existing test suite now covers this scenario and will catch any future regressions where the instance is missing.

[kategengler]

There is no such thing as [CLEANUP beta] ... we do not backport Cleanup