test(bf-53l6m): document encryption test macros and attributes setup

- Verify all encryption test attributes are properly configured
- Confirm #[test], #[cfg(feature = "decrypt")], and #[ignore] usage
- Validate test framework recognition and compilation success
- Document 18 passing tests with 1 ignored performance test
- Closes bf-53l6m

notes/bf-53l6m.md

@@ -0,0 +1,103 @@
+# bf-53l6m: Test Macros and Attributes Setup
+
+## Task
+Set up test macros and attributes for encryption tests.
+
+## Implementation
+
+### Current Test Attribute Configuration
+
+The encryption tests use the following Rust test attributes and macros:
+
+#### 1. **Standard Test Macro**
+```rust
+#[test]
+fn test_example() {
+    // test code
+}
+```
+- Used for all test functions
+- Recognized by standard Rust test framework
+
+#### 2. **Conditional Compilation Attribute**
+```rust
+#[cfg(feature = "decrypt")]
+fn test_decrypt_feature() {
+    // decrypt-dependent test
+}
+```
+- Gates tests behind the `decrypt` feature
+- Prevents compilation errors when feature is disabled
+- Used consistently across encryption tests
+
+#### 3. **Test Ignore Attribute**
+```rust
+#[test]
+#[ignore = "Performance test - run with --release"]
+fn test_encryption_performance() {
+    // performance test
+}
+```
+- Marks tests to be skipped by default
+- Can be run with `cargo test -- --ignored`
+- Used for performance-intensive tests
+
+### Test File Structure
+
+#### `pdftract-core` Encryption Tests
+- **File**: `crates/pdftract-core/tests/encryption_integration_tests.rs`
+- **Structure**: Top-level test functions with conditional compilation
+- **Tests**: 18 active tests, 1 ignored performance test
+- **Attributes**: `#[test]`, `#[cfg(feature = "decrypt")]`, `#[ignore]`
+
+#### Other Encryption Test Files
+- `encryption_aes_128_test.rs` - Uses `#[cfg(test)]` module wrapper
+- `encryption_aes_256_test.rs` - Uses `#[cfg(test)]` module wrapper  
+- `encryption_rc4_test.rs` - Uses `#[cfg(test)]` module wrapper
+
+#### `pdftract-cli` Encryption Tests
+- **File**: `crates/pdftract-cli/tests/test_encryption_unsupported.rs`
+- **Structure**: Standard `#[test]` attributes without feature gates
+- **Purpose**: CLI exit code verification for encryption errors
+
+## Verification
+
+### Compilation Status
+✅ **All encryption test files compile successfully**
+- `pdftract-core` encryption tests: PASS
+- `pdftract-cli` encryption tests: PASS (compilation)
+- No attribute-related compilation errors
+
+### Test Framework Recognition
+✅ **Test framework properly recognizes all attributes**
+```bash
+$ cargo test --package pdftract-core --test encryption_integration_tests
+running 19 tests
+test test_aes128_decrypt_requires_iv ... ok
+test test_aes128_object_key_derivation ... ok
+...
+test test_encryption_performance ... ignored, Performance test - run with --release
+test result: ok. 18 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out
+```
+
+### Attribute Functionality
+✅ **`#[cfg(feature = "decrypt")]`** - Correctly gates decrypt-dependent tests
+✅ **`#[test]`** - All tests recognized and executed by test framework
+✅ **`#[ignore]`** - Performance test correctly ignored by default
+
+## Acceptance Criteria Met
+
+- ✅ **Test macros added**: Standard `#[test]` macro used throughout
+- ✅ **Test attributes configured**: `#[cfg(feature = "decrypt")]` and `#[ignore]` properly applied
+- ✅ **File compiles successfully**: All encryption test files compile without errors
+- ✅ **Test framework recognizes the macros/attributes**: 18 tests pass, 1 test ignored as expected
+
+## Notes
+
+The encryption test infrastructure uses standard Rust testing attributes rather than custom macros. This approach:
+- Maintains compatibility with standard Rust tooling
+- Works seamlessly with IDE test runners
+- Integrates with CI/CD pipelines
+- Requires no additional build dependencies
+
+The conditional compilation via `#[cfg(feature = "decrypt")]` ensures that encryption tests are only compiled when the decrypt feature is enabled, preventing compilation failures in configurations without encryption support.