zircon/kernel/tests/rustlang-support/rust-tests.cc

// Copyright 2026 The Fuchsia Authors
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT

#include <lib/unittest/unittest.h>
#include <stdint.h>

// This file has tests of the Rust build support and fundamental features of
// the compiler and cross-language linkage support.  It is not a place to put
// tests for other kernel code that happens to be in Rust.

extern "C" {  // Defined in Rust (src/lib.rs).

int32_t add_one_in_rust(int32_t);

extern const int32_t kConstVarDefinedInRust;

extern int32_t gVarDefinedInRust;

extern const int32_t kConstVarExportedToRust = 23;
int32_t get_const_var_exported_to_rust();

int32_t gVarExportedToRust;
int32_t fetch_add_var_exported_to_rust(int32_t);

}  // extern "C"

extern "C" int32_t rust_mod_fn();

namespace {

bool add_one_test() {
  BEGIN_TEST;
  EXPECT_EQ(add_one_in_rust(42), 43);
  END_TEST;
}

bool defined_const_test() {
  BEGIN_TEST;
  EXPECT_EQ(kConstVarDefinedInRust, 17);
  END_TEST;
}

bool exported_const_test() {
  BEGIN_TEST;
  EXPECT_EQ(get_const_var_exported_to_rust(), 23);
  END_TEST;
}

bool defined_var_test() {
  BEGIN_TEST;
  EXPECT_EQ(gVarDefinedInRust, 42);
  END_TEST;
}

bool exported_var_test() {
  BEGIN_TEST;
  gVarExportedToRust = 17;
  EXPECT_EQ(fetch_add_var_exported_to_rust(23), 17);
  EXPECT_EQ(gVarExportedToRust, 40);
  END_TEST;
}

bool rust_mod_test() {
  BEGIN_TEST;
  EXPECT_EQ(rust_mod_fn(), 42);
  END_TEST;
}

UNITTEST_START_TESTCASE(rust_compilation_tests)
UNITTEST("test a trivial Rust function called from C++", add_one_test)
UNITTEST("test a Rust-defined global variable read from C++", defined_const_test)
UNITTEST("test a C++-defined global variable read from Rust", exported_const_test)
UNITTEST("test a Rust-defined global variable written from C++", defined_var_test)
UNITTEST("test a C++-defined global variable written from Rust", exported_var_test)
UNITTEST("test a trivial Rust function via kernel_rust_mod()", rust_mod_test)
UNITTEST_END_TESTCASE(rust_compilation_tests, "rust", "Tests for Rust compilation")

}  // namespace