Add C++ golden file test suite - #223
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Jason can you take a look? You can ignore the generated |
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LGTM % minor copyright header nits
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This change introduces a robust, granular testing infrastructure for the C++ backend using golden files. This test suite serves as a critical safety net to enable safe and efficient refactoring of the code generator in the future. By comparing generated code against a set of "golden" (known-good) header files, we can quickly detect any unintended changes or regressions. Key Features: * **Granular Tests:** Each golden file comparison is a standalone `py_test` target, allowing for parallel execution and precise failure identification. * **`cpp_golden_test` Macro:** A new Starlark macro, `cpp_golden_test`, has been added to `compiler/back_end/cpp/build_defs.bzl`. This simplifies adding new golden tests by abstracting away the underlying `py_test` implementation details. * **Debugging:** To simplify the diagnosis of regressions, test failures produce a `diff` of the generated file against its golden counterpart. * **Full Coverage:** The suite includes tests for all `.emb` files in the `testdata` directory, including those with complex dependencies and imports. Usage: **To run all C++ golden tests:** ``` bazel test //compiler/back_end/cpp/... --test_tag_filters=golden ``` **To run a single golden test:** ``` bazel test //compiler/back_end/cpp:bits_golden_test ``` **To add a new golden test:** 1. Add your `.emb` file to `testdata/`. 2. Generate the corresponding golden `.emb.h` file (e.g., by temporarily modifying and running the `generate_golden_files.sh` script via a `sh_binary`). 3. Copy the new golden file into `testdata/golden_cpp/`. 4. Add a `cpp_golden_test()` rule to `compiler/back_end/cpp/BUILD`.
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This change introduces a robust, granular testing infrastructure for the C++ backend using golden files. This test suite serves as a critical safety net to enable safe and efficient refactoring of the code generator in the future.
By comparing generated code against a set of "golden" (known-good) header files, we can quickly detect any unintended changes or regressions.
Key Features:
py_testtarget, allowing for parallel execution and precise failure identification.cpp_golden_testMacro: A new Starlark macro,cpp_golden_test, has been added tocompiler/back_end/cpp/build_defs.bzl. This simplifies adding new golden tests by abstracting away the underlyingpy_testimplementation details.diffof the generated file against its golden counterpart..embfiles in thetestdatadirectory, including those with complex dependencies and imports.Usage:
To run all C++ golden tests:
To run a single golden test:
To add a new golden test:
.embfile totestdata/..emb.hfile (e.g., by temporarily modifying and running thegenerate_golden_files.shscript via ash_binary).testdata/golden_cpp/.cpp_golden_test()rule tocompiler/back_end/cpp/BUILD.