kotlin-rust-test-parity.md

Kotlin-to-Rust test parity

This document tracks the Kotlin test suite against the experimental Rust implementation. Consolidated means one Rust test validates the same bazel-diff-owned contract as several Kotlin examples. Tests that only validate Kotlin/JVM implementation mechanics, dependency-injection wiring, or behavior guaranteed by Rust's type system or an external crate are marked non-applicable rather than copied.

Rust unit tests do not create executables that impersonate Bazel. Query planning, repository lowering, and module-impact decisions are tested as pure transformations with injected data; subprocess integration is covered by the real-Bazel E2E suite.

Kotlin test class	Rust coverage	Status / non-applicable details
bazel/BazelClientTest	Query/cquery, external fallback, filtering, deduplication, and Bzlmod tests in src/bazel.rs	Consolidated
bazel/BazelModServiceTest	Bazel version/module-graph command tests in src/bazel.rs	Consolidated
bazel/BazelRuleTest	Rule input, digest, tag, visibility, and external-label tests in src/bazel.rs and src/hash.rs	Consolidated
bazel/BazelTargetTest	target_names_and_lowering_cover_all_target_types	Ported
bazel/BazelTargetTypeTest	Generated protobuf discriminators are exercised by target-lowering tests	Kotlin enum reflection is non-applicable
bazel/ModuleGraphParserTest	Parsing, cycle, edge, change, and fallback tests in src/bazel.rs and src/module_graph.rs	Consolidated
bazel/StderrPollutionRegressionTest	Prefixed JSON parsing and unchanged-graph fast paths in src/module_graph.rs	Consolidated
cli/BazelDiffTest	Compatibility argument normalization and command workflow tests in src/main.rs	Consolidated; Clap's own required-subcommand/default behavior is not retested
cli/converter/ByteSizeConverterTest	parses_binary_byte_size	Ported
cli/converter/CommaSeparatedValueConverterTest	No custom Rust converter exists	Clap delimiter behavior is external-crate behavior
cli/converter/DurationConverterTest	parses_compound_duration	Ported
cli/converter/NormalisingPathConverterTest	option_and_path_compatibility_helpers_normalize_values	Ported
cli/converter/OptionsConverterTest	option_and_path_compatibility_helpers_normalize_values	Ported
cli/FingerprintCommandTest	Fingerprint command workflow and output tests in src/main.rs and src/fingerprint.rs	Consolidated
cli/FingerprintGathererTest	Gather/import/version tests in src/fingerprint.rs	Ported
cli/ServeCommandTest	Serve configuration, cache, readiness, metrics, and routing tests in src/main.rs and src/server.rs	Consolidated; JVM shutdown-hook/Koin lifecycle mechanics are non-applicable
cli/VersionProviderTest	Rust version is compile-time CARGO_PKG_VERSION	JVM classpath-resource fallback is non-applicable
cli/WarmupCommandTest	Warmup success/failure and artifact-ordering tests in src/main.rs	Ported
e2e/E2ETest	tests/e2e/{core,external,regressions}.rs	Ported; the C++ Bzlmod case is ignored for the same Bazel 7 fixture/Bazel 8+ incompatibility documented by Kotlin
hash/BuildGraphHasherTest	Integrated graph hashing tests in src/hash.rs	Consolidated; Kotlin's phase-timing object is non-applicable
hash/RuleHasherAlwaysAffectedTagsTest	Always-affected and stable untagged paths in src/hash.rs	Consolidated
hash/RuleHasherTest	Cycle, memoization, source, visibility, cquery, and dependency-tracking tests in src/hash.rs	Consolidated
hash/SourceFileHasherTest	Content, executable-bit, external, missing-file, and label-form tests in src/hash.rs	Consolidated; Koin-constructor test is non-applicable
hash/TargetHashTest	Parsing and serialization tests in src/model.rs	Ported
interactor/CalculateImpactedTargetsInteractorIssue335Test	Extension/sub-string repository regression test in src/module_graph.rs	Ported
interactor/CalculateImpactedTargetsInteractorModuleQueryTest	Query success, removed-module, mixed-workspace, and Bzlmod-only fallback tests in src/module_graph.rs	Consolidated
interactor/CalculateImpactedTargetsInteractorTest	Distance/filter/sort tests in src/model.rs and module-change tests in src/module_graph.rs	Consolidated
interactor/DeserialiseHashesInteractorTest	Legacy/metadata read and malformed-input tests in src/model.rs	Consolidated
interactor/FingerprintInteractorTest	Deterministic/component sensitivity tests in src/fingerprint.rs	Consolidated
io/ContentHashProviderTest	hash_options_load_content_hashes_and_validate_shape	Ported
log/StderrLoggerTest	Rust has no logger abstraction; observable warning/error fallback paths are tested	Kotlin logger implementation is non-applicable
process/ProcessStdinHangRegressionTest	All Rust subprocess call sites explicitly use Stdio::null()	std::process EOF behavior is not retested
server/BazelDiffServerTest	Loopback routing, profile, distance, readiness, method, and timeout tests in src/server.rs	Consolidated
server/CachePrunerTest	Disabled and age/count/size pruning tests in src/server.rs	Consolidated; JVM scheduler interruption mechanics are non-applicable
server/GitClientTest	Real Git resolve, checkout, stale-lock recovery, and multi-remote targeted-fetch tests in src/server.rs	Consolidated
server/HashServiceTest	Cache-key, local/remote hit, backfill, metadata, and profile tests in src/server.rs	Consolidated
server/ImpactedTargetsServiceTest	Profiled query, distance, refetch, and route tests in src/server.rs	Consolidated
server/LocalDiskHashCacheStorageTest	Local hit/touch/stats and age/count/size pruning tests in src/server.rs	Consolidated
server/MetricsServiceTest	metrics_and_human_sizes_report_cache_state	Consolidated; JVM heap/clock injection is non-applicable
server/QueryProfilerTest	Profiled query response tests in src/server.rs	Consolidated; JVM GC-bean accounting is non-applicable
server/S3HashCacheStorageTest	Real loopback S3 success/miss/error and normalized-key tests in src/server.rs	Consolidated; rust-s3 request construction itself is not retested
server/TieredHashCacheStorageTest	Remote backfill/local reuse and local pruning behavior in src/server.rs	Consolidated

Enforcement

• //:rust_tests runs both //src:rust_tests and //src:cli_tests.
• //src:rust_tests enforces at least 90% Rust production line coverage through //tools/coverage:lcov_merger.
• Rust E2E parity lives under tests/e2e.rs and runs in the dedicated CI E2E job.