Add test that asserts behavior for when we try to renderComponent into the same element multiple times

[NullVoxPopuli]

from the RFC: https://rfcs.emberjs.com/id/1099-rendercomponent/

Repeat calls to renderComponent with the same element will replace all contents on that element.

This is changed because implementation of the renderer did append (and it was easier)

• Updates to renderComponent from implementation rfcs#1166

[github-actions]

Estimated Asset Sizes

Diff

--- main/out.txt	2026-02-10 02:24:22.000000000 +0000
+++ pr/./pr-21853935459/out.txt	2026-02-10 06:14:50.000000000 +0000
@@ -1,34 +1,34 @@
 ╔═══════╤═══════════╤═══════════╗
 ║       │ Min       │ Gzip      ║
 ╟───────┼───────────┼───────────╢
-║ Total │ 352.48 KB │ 203.69 KB ║
+║ Total │ 352.48 KB │ 203.64 KB ║
 ╚═══════╧═══════════╧═══════════╝
 
 ╔══════════════════════╤═══════════╤═══════════╗
 ║ @ember/*             │ Min       │ Gzip      ║
 ╟──────────────────────┼───────────┼───────────╢
-║ Total                │ 313.87 KB │ 181.83 KB ║
+║ Total                │ 313.87 KB │ 181.79 KB ║
 ╟──────────────────────┼───────────┼───────────╢
-║ -internals           │ 36.68 KB  │ 25.99 KB  ║
-║ application          │ 13.24 KB  │ 7.99 KB   ║
+║ -internals           │ 36.68 KB  │ 26.02 KB  ║
+║ application          │ 13.24 KB  │ 8.04 KB   ║
 ║ array                │ 13.05 KB  │ 7.54 KB   ║
 ║ canary-features      │ 304 B     │ 419 B     ║
-║ component            │ 2.05 KB   │ 1.63 KB   ║
+║ component            │ 2.05 KB   │ 1.59 KB   ║
 ║ controller           │ 1.96 KB   │ 1.45 KB   ║
 ║ debug                │ 11.73 KB  │ 8.14 KB   ║
 ║ deprecated-features  │ 31 B      │ 77 B      ║
 ║ destroyable          │ 561 B     │ 383 B     ║
 ║ enumerable           │ 259 B     │ 387 B     ║
-║ helper               │ 1.08 KB   │ 841 B     ║
+║ helper               │ 1.08 KB   │ 816 B     ║
 ║ instrumentation      │ 2.43 KB   │ 1.78 KB   ║
-║ modifier             │ 1.22 KB   │ 991 B     ║
+║ modifier             │ 1.22 KB   │ 993 B     ║
 ║ object               │ 35.98 KB  │ 22.1 KB   ║
 ║ owner                │ 159 B     │ 178 B     ║
-║ renderer             │ 630 B     │ 509 B     ║
-║ routing              │ 59.37 KB  │ 33.94 KB  ║
+║ renderer             │ 630 B     │ 503 B     ║
+║ routing              │ 59.37 KB  │ 33.93 KB  ║
 ║ runloop              │ 2.36 KB   │ 1.5 KB    ║
 ║ service              │ 1 KB      │ 858 B     ║
-║ template             │ 654 B     │ 535 B     ║
+║ template             │ 654 B     │ 501 B     ║
 ║ template-compilation │ 429 B     │ 366 B     ║
 ║ template-compiler    │ 123.33 KB │ 59.61 KB  ║
 ║ template-factory     │ 370 B     │ 385 B     ║

Details

This PR

main

╔═══════╤═══════════╤═══════════╗ ║ │ Min │ Gzip ║ ╟───────┼───────────┼───────────╢ ║ Total │ 352.48 KB │ 203.64 KB ║ ╚═══════╧═══════════╧═══════════╝ ╔══════════════════════╤═══════════╤═══════════╗ ║ @ember/* │ Min │ Gzip ║ ╟──────────────────────┼───────────┼───────────╢ ║ Total │ 313.87 KB │ 181.79 KB ║ ╟──────────────────────┼───────────┼───────────╢ ║ -internals │ 36.68 KB │ 26.02 KB ║ ║ application │ 13.24 KB │ 8.04 KB ║ ║ array │ 13.05 KB │ 7.54 KB ║ ║ canary-features │ 304 B │ 419 B ║ ║ component │ 2.05 KB │ 1.59 KB ║ ║ controller │ 1.96 KB │ 1.45 KB ║ ║ debug │ 11.73 KB │ 8.14 KB ║ ║ deprecated-features │ 31 B │ 77 B ║ ║ destroyable │ 561 B │ 383 B ║ ║ enumerable │ 259 B │ 387 B ║ ║ helper │ 1.08 KB │ 816 B ║ ║ instrumentation │ 2.43 KB │ 1.78 KB ║ ║ modifier │ 1.22 KB │ 993 B ║ ║ object │ 35.98 KB │ 22.1 KB ║ ║ owner │ 159 B │ 178 B ║ ║ renderer │ 630 B │ 503 B ║ ║ routing │ 59.37 KB │ 33.93 KB ║ ║ runloop │ 2.36 KB │ 1.5 KB ║ ║ service │ 1 KB │ 858 B ║ ║ template │ 654 B │ 501 B ║ ║ template-compilation │ 429 B │ 366 B ║ ║ template-compiler │ 123.33 KB │ 59.61 KB ║ ║ template-factory │ 370 B │ 385 B ║ ║ test │ 923 B │ 627 B ║ ║ utils │ 4.11 KB │ 3.63 KB ║ ║ version │ 55 B │ 131 B ║ ╚══════════════════════╧═══════════╧═══════════╝ ╔═════════════════╤══════════╤══════════╗ ║ @glimmer/* │ Min │ Gzip ║ ╟─────────────────┼──────────┼──────────╢ ║ Total │ 38.61 KB │ 21.86 KB ║ ╟─────────────────┼──────────┼──────────╢ ║ destroyable │ 2.78 KB │ 1.38 KB ║ ║ encoder │ 81 B │ 171 B ║ ║ env │ 38 B │ 87 B ║ ║ global-context │ 886 B │ 545 B ║ ║ manager │ 977 B │ 627 B ║ ║ node │ 175 B │ 268 B ║ ║ opcode-compiler │ 1.11 KB │ 905 B ║ ║ owner │ 159 B │ 202 B ║ ║ program │ 252 B │ 308 B ║ ║ reference │ 548 B │ 544 B ║ ║ runtime │ 10.32 KB │ 5.21 KB ║ ║ tracking │ 1.34 KB │ 1.18 KB ║ ║ util │ 1.94 KB │ 1.6 KB ║ ║ validator │ 15.75 KB │ 7 KB ║ ║ vm │ 495 B │ 569 B ║ ║ wire-format │ 1.84 KB │ 1.35 KB ║ ╚═════════════════╧══════════╧══════════╝

╔═══════╤═══════════╤═══════════╗ ║ │ Min │ Gzip ║ ╟───────┼───────────┼───────────╢ ║ Total │ 352.48 KB │ 203.69 KB ║ ╚═══════╧═══════════╧═══════════╝ ╔══════════════════════╤═══════════╤═══════════╗ ║ @ember/* │ Min │ Gzip ║ ╟──────────────────────┼───────────┼───────────╢ ║ Total │ 313.87 KB │ 181.83 KB ║ ╟──────────────────────┼───────────┼───────────╢ ║ -internals │ 36.68 KB │ 25.99 KB ║ ║ application │ 13.24 KB │ 7.99 KB ║ ║ array │ 13.05 KB │ 7.54 KB ║ ║ canary-features │ 304 B │ 419 B ║ ║ component │ 2.05 KB │ 1.63 KB ║ ║ controller │ 1.96 KB │ 1.45 KB ║ ║ debug │ 11.73 KB │ 8.14 KB ║ ║ deprecated-features │ 31 B │ 77 B ║ ║ destroyable │ 561 B │ 383 B ║ ║ enumerable │ 259 B │ 387 B ║ ║ helper │ 1.08 KB │ 841 B ║ ║ instrumentation │ 2.43 KB │ 1.78 KB ║ ║ modifier │ 1.22 KB │ 991 B ║ ║ object │ 35.98 KB │ 22.1 KB ║ ║ owner │ 159 B │ 178 B ║ ║ renderer │ 630 B │ 509 B ║ ║ routing │ 59.37 KB │ 33.94 KB ║ ║ runloop │ 2.36 KB │ 1.5 KB ║ ║ service │ 1 KB │ 858 B ║ ║ template │ 654 B │ 535 B ║ ║ template-compilation │ 429 B │ 366 B ║ ║ template-compiler │ 123.33 KB │ 59.61 KB ║ ║ template-factory │ 370 B │ 385 B ║ ║ test │ 923 B │ 627 B ║ ║ utils │ 4.11 KB │ 3.63 KB ║ ║ version │ 55 B │ 131 B ║ ╚══════════════════════╧═══════════╧═══════════╝ ╔═════════════════╤══════════╤══════════╗ ║ @glimmer/* │ Min │ Gzip ║ ╟─────────────────┼──────────┼──────────╢ ║ Total │ 38.61 KB │ 21.86 KB ║ ╟─────────────────┼──────────┼──────────╢ ║ destroyable │ 2.78 KB │ 1.38 KB ║ ║ encoder │ 81 B │ 171 B ║ ║ env │ 38 B │ 87 B ║ ║ global-context │ 886 B │ 545 B ║ ║ manager │ 977 B │ 627 B ║ ║ node │ 175 B │ 268 B ║ ║ opcode-compiler │ 1.11 KB │ 905 B ║ ║ owner │ 159 B │ 202 B ║ ║ program │ 252 B │ 308 B ║ ║ reference │ 548 B │ 544 B ║ ║ runtime │ 10.32 KB │ 5.21 KB ║ ║ tracking │ 1.34 KB │ 1.18 KB ║ ║ util │ 1.94 KB │ 1.6 KB ║ ║ validator │ 15.75 KB │ 7 KB ║ ║ vm │ 495 B │ 569 B ║ ║ wire-format │ 1.84 KB │ 1.35 KB ║ ╚═════════════════╧══════════╧══════════╝

[NullVoxPopuli]

I think I need more tests -- I want to make sure updating renderComponents can update appropriately

if so, this could resolve a potentially contentious issue on the RFC (brought up by @void-mAlex and @lifeart , I think?)

since the current behavior is not what the RFC states, we could update the RFC and implement replace behavior.

I wrote that replace behavior would be the behavior because I thought it would be easier 🙈

[lifeart]

I'm afrade replace behaviour is dangerous itself, because we don't know who owns "replaced" nodes, it may cause memory leaks. I think we should append by default, or renderBefore, renderAfter target node (as discussed in rfc)

[NullVoxPopuli]

that makes sense to me and I'm happy with that direction

[NullVoxPopuli]

I've added enough tests to assert append / sibling behavior -- however found a bug where if an update happens to the data used by the first (in DOM order) component, it gets moved to the bottom of the output element. This is probably very jarring if anyone has tried this usecase today.

[NullVoxPopuli]

the firstNode here is really the fix for the bug found be the second test in this PR

Big changes occurred since you're last review -- could you re-review?