[GR-71342] Test tier run through

PullRequest: graalpython/4227

Author: ban-mi

docs/user/Test-Tiers.md

@@ -1,53 +1,62 @@
 # Detailed Test Tier Breakdown
 
-GraalPy test tiers are similar to [CPython Platform Support Tiers](https://peps.python.org/pep-0011/), but do not constitute or imply any commitment to support.
+GraalPy organizes platform testing into tiers that indicate the level of testing rigor and support you can expect for different platform configurations. This tiering system helps you understand:
 
-Generally, running pure Python code on GraalPy without JIT is compatible with any recent JDK.
-However, support for native extensions, platform-specific APIs, and just-in-time compilation is more limited.
+- How thoroughly your platform is tested
+- What level of stability to expect
+- Which features are fully supported vs. experimental
 
-Platform testing is organized into Tiers, each with specific goals.
-Tiers are identified by a "target tuple": `[CPU architecture]-[Operating System]-[libc]-[JDK]-[Java version]`.
-JDK names correspond to those used by [SDKMAN!](https://sdkman.io/).
-The term "graal" is used to refer to testing on both Oracle GraalVM and GraalVM Community Edition, including GraalVM Native Image.
-The following tables list tested platforms by tier.
-Platforms not listed are untested.
+Platforms are identified using the target tuple format: `[CPU architecture]-[Operating System]-[libc]-[JDK]-[Java version]`. JDK names follow [SDKMAN!](https://sdkman.io/) conventions, and "graal" refers to both Oracle GraalVM and GraalVM Community Edition (including Native Image).
 
-**Tier 1**
+> **Important:** GraalPy test tiers are similar to [CPython Platform Support Tiers](https://peps.python.org/pep-0011/), but do not constitute or imply any commitment to support.
 
-- CI failures block releases.
-- Changes which would break the main or release branches are not allowed to be merged; any breakage should be fixed or reverted immediately.
-- All core developers are responsible to keep main, and thus these platforms, working.
-- Platform-specific Python APIs and Python C extensions are fully tested.
+Pure Python code runs reliably on GraalPy with recent JDKs when JIT compilation is disabled. However, advanced features like native extensions, platform-specific APIs, and JIT compilation have varying support depending on your platform tier.
+
+## Tier 1
+
+- **Stability:** CI failures block releases. Changes which would break the main or release branches are not allowed to be merged; any breakage should be fixed or reverted immediately.
+- **Responsibility:** All core developers are responsible to keep main, and thus these platforms, working.
+- **Coverage:** Platform-specific Python APIs and Python C extensions are fully tested.
 
 | Platform                         | Notes                      |
 |----------------------------------|----------------------------|
 | amd64-linux-glibc-graal-latest   | Oracle Linux 8 or similar. |
 | aarch64-linux-glibc-graal-latest | Oracle Linux 8 or similar. |
 
-**Tier 2**
+## Tier 2
 
-- CI failures block releases.
-- Changes which would break the main or release branches are not allowed to be merged; any breakage should be fixed or tests marked as skipped.
-- Circa 10% of tests running on Tier 1 platforms may be skipped on Tier 2 platforms.
-- Platform-specific Python APIs are fully tested; Python C extensions may have more issues than on Tier 1 platforms.
+- **Stability:** CI failures block releases. Changes which would break the main or release branches are not allowed to be merged; any breakage should be fixed or tests marked as skipped.
+- **Test Coverage:** Circa 10% of tests running on Tier 1 platforms may be skipped on Tier 2 platforms.
+- **Feature Support:** Platform-specific Python APIs are fully tested; Python C extensions may have more issues than on Tier 1 platforms.
 
 | Platform                          | Notes                   |
 |-----------------------------------|-------------------------|
 | aarch64-macos-darwin-graal-latest | macOS on M-series CPUs. |
 
-**Tier 3**
+## Tier 3
 
-- CI failures block releases.
-- Changes which would break the main or release branches are not allowed to be merged; any breakage should be fixed or tests marked as skipped.
-- Circa 25% of tests running on Tier 1 platforms may be skipped on Tier 3.
-- Tests for platform-specific Python APIs and Python C extension are run, but not prioritized.
+- **Stability:** CI failures block releases. Changes which would break the main or release branches are not allowed to be merged; any breakage should be fixed or tests marked as skipped.
+- **Test Coverage:** Circa 25% of tests running on Tier 1 platforms may be skipped on Tier 3.
+- **Feature Support:** Tests for platform-specific Python APIs and Python C extension are run, but not prioritized.
 
 | Platform                        | Notes                                        |
 |---------------------------------|----------------------------------------------|
-| amd64-macos-darwin-graal-latest | macOS on Intel CPUs running BigSur or newer. |
+| amd64-macos-darwin-graal-latest | macOS on Intel CPUs running Big Sur or newer. |
 | amd64-windows-msvc-graal-latest | Windows 11, Windows Server 2025, or newer.   |
 | amd64-linux-glibc-oracle-21     | JDK 21 is tested without JIT compilation.    |
 | aarch64-linux-glibc-oracle-21   | JDK 21 is tested without JIT compilation.    |
 | aarch64-macos-darwin-oracle-21  | JDK 21 is tested without JIT compilation.    |
 | amd64-macos-darwin-oracle-21    | JDK 21 is tested without JIT compilation.    |
 | amd64-windows-msvc-oracle-21    | JDK 21 is tested without JIT compilation.    |
+
+## Tier 4
+
+- **Stability:** CI failures do not block releases. Tests may be broken on the main and release branches.
+- **Test Coverage:** Smoke tests with platform-agnostic pure Python workloads are run on a regular schedule.
+- **Feature Support:** Only basic pure Python functionality is tested; platform-specific features and extensions are not prioritized.
+
+| Platform                        | Notes                                         |
+| ------------------------------- | ----------------------------------------------|
+| amd64-linux-musl-graal-latest   | Ensures GraalPy can be built for and used on musl libc platforms such as Alpine Linux. |
+| amd64-linux-glibc-j9-17         | Ensures that non-Oracle JVMs work for pure Python code without JIT. |
+| ppc64le-linux-glibc-oracle-17   | Ensures that other architectures (ppc64le, s390x, risc-v) work for pure Python code without JIT. |