Clarify @test throws-clause review guidance

Author: trask

.github/agents/code-review-and-fix.agent.md

@@ -156,6 +156,8 @@ Auto-fix boundaries:
     already valid AssertJ assertions; do not wrap them in `assertThat(...).isTrue()`
   - AssertJ `.as(...)` descriptions and `.withFailMessage(...)` in tests — remove them
     and prefer direct assertions whose failure output already exposes the unexpected values
+  - `@Test` method `throws` clauses — limit them to a single exception type and keep that type as
+    specific as possible.
   - deterministic semconv constant handling aligned with repository rules
   - missing test-task wiring patterns with clear canonical form
   - missing `testInstrumentation` cross-version references — when a javaagent module belongs

.github/agents/knowledge/README.md

@@ -18,7 +18,7 @@ Load only files relevant to the current scope to reduce noise and avoid over-con
 | `javaagent-singletons-patterns.md` | `*Singletons` holder classes, singleton accessors, callers of singleton accessors/fields |
 | `library-patterns.md` | Library instrumentation telemetry, builder, getter, or setter pattern changes |
 | `module-naming.md` | New or renamed modules or packages; settings includes |
-| `testing-general-patterns.md` | Test files in scope — assertion style, resource cleanup patterns, attribute assertion patterns, `satisfies()` lambda usage |
+| `testing-general-patterns.md` | Test files in scope — assertion style, test method signatures and throws clauses, resource cleanup patterns, attribute assertion patterns, `satisfies()` lambda usage |
 | `testing-experimental-flags.md` | `testExperimental` task or experimental span-attribute assertions |
 | `testing-semconv-stability.md` | Semconv opt-in modes, `emitOld*`/`emitStable*`, `maybeStable`, Semconv test tasks |
 

.github/agents/knowledge/general-rules.md

@@ -25,7 +25,7 @@ When a "Knowledge File" is listed, load it from `knowledge/` before reviewing th
 | Javaagent | Incorrect `classLoaderMatcher()` | `classLoaderMatcher()` override that is redundant (muzzle already handles it) or missing when needed (muzzle cannot distinguish version range) | `javaagent-module-patterns.md` |
 | Semconv | Library vs javaagent semconv constant usage | Semconv constants/assertions | — |
 | Semconv | Dual semconv testing | `SemconvStability`, `maybeStable`, semconv Gradle tasks | `testing-semconv-stability.md` |
-| Testing | General test patterns | Test files in scope — assertion style, resource cleanup, attribute assertions | `testing-general-patterns.md` |
+| Testing | General test patterns | Test files in scope — assertion style, test method signatures and throws clauses, resource cleanup, attribute assertions | `testing-general-patterns.md` |
 | Testing | Experimental flag tests | `testExperimental`, experimental attribute assertions, `experimental` flags in JVM args or system properties | `testing-experimental-flags.md` |
 | Library | TelemetryBuilder/getter/setter patterns | Library instrumentation classes | `library-patterns.md` |
 | API | Deprecation and breaking-change policy | Public API changes | `api-deprecation-policy.md` |

.github/agents/knowledge/testing-general-patterns.md

@@ -3,7 +3,7 @@
 ## Quick Reference
 
 - Use when: test files (`**/src/test/**`) are in scope
-- Review focus: assertion style, test class visibility, resource cleanup patterns, attribute assertion patterns
+- Review focus: assertion style, test class visibility, test method signatures and throws clauses, resource cleanup patterns, attribute assertion patterns
 
 ## Assertion Framework
 
@@ -12,6 +12,16 @@
 - Do not use AssertJ `.as(...)` descriptions or `.withFailMessage(...)` in tests.
   Prefer direct assertions whose failure output shows the unexpected values.
 
+## Test Method Throws Clauses
+
+- On methods annotated with `@Test`, keep the `throws` clause to a single exception type.
+  Do not declare multiple checked exception types on a test method.
+- Be as specific as possible. Prefer the narrowest single checked type that the test body
+  actually exposes instead of broad forms such as `throws Exception` or a multi-exception list.
+- If the test only blocks on `Future.get(...)` / `CompletableFuture.get(...)`, prefer refactoring to
+  `join()` or another non-checked wait path when that keeps the test clear, rather than widening the
+  test method to `throws Exception` just to avoid a multi-exception `throws` clause.
+
 ## Test Resource Cleanup
 
 - In JUnit tests, when an `AutoCloseable` is intended to remain live for most or all of the test