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ExceptionOr<T>::ok() returns true if the value is set. This can be misleading
for boolean types.
ExceptionOr<bool> result = SomeFunction();
if (result.ok()) {
if (result.result() {
// Case 1: SomeFunction returned true
} else {
// Case 2: SomeFunction returned false
} else {
// Case 3: SomeFunction returned an exception
}
It's easy to overlook case 2.
The specialized ExceptionOr<bool>::ok() returns false in Case 2, which allows
us to write:
if (result) {
// SomeFunction returned true
} else {
// SomeFunction returned false or an exception
// result.GetException() can be used if we need to handle different exceptions
// differenty
}
PiperOrigin-RevId: 544715641
140 lines
4.5 KiB
C++
140 lines
4.5 KiB
C++
// Copyright 2020 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "internal/platform/exception.h"
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#include <vector>
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#include "gmock/gmock.h"
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#include "protobuf-matchers/protocol-buffer-matchers.h"
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#include "gtest/gtest.h"
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#include "internal/platform/exception_test.nc.h"
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namespace nearby {
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TEST(ExceptionOr, Result_Copy_NonConst) {
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ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
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EXPECT_FALSE(exception_or_vector.result().empty());
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// Expect a copy when not explicitly moving the result.
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std::vector<int> copy = exception_or_vector.result();
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EXPECT_FALSE(copy.empty());
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EXPECT_FALSE(exception_or_vector.result().empty());
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// Modifying |exception_or_vector| should not affect the copy.
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exception_or_vector.result().clear();
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EXPECT_FALSE(copy.empty());
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}
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TEST(ExceptionOr, Result_Copy_Const) {
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const ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
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EXPECT_FALSE(exception_or_vector.result().empty());
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// Expect a copy when not explicitly moving the result.
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const std::vector<int>& copy = exception_or_vector.result();
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EXPECT_FALSE(copy.empty());
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EXPECT_FALSE(exception_or_vector.result().empty());
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}
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TEST(ExceptionOr, Result_Reference_NonConst) {
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ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
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EXPECT_FALSE(exception_or_vector.result().empty());
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// Getting a reference should not modify the source.
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std::vector<int>& reference = exception_or_vector.result();
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EXPECT_FALSE(reference.empty());
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EXPECT_FALSE(exception_or_vector.result().empty());
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// Modifying |exception_or_vector| should reflect in the reference.
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exception_or_vector.result().clear();
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EXPECT_TRUE(reference.empty());
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}
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TEST(ExceptionOr, Result_Reference_Const) {
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const ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
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EXPECT_FALSE(exception_or_vector.result().empty());
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// Getting a reference should not modify the source.
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const std::vector<int>& reference = exception_or_vector.result();
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EXPECT_FALSE(reference.empty());
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EXPECT_FALSE(exception_or_vector.result().empty());
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}
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TEST(ExceptionOr, Result_Move_NonConst) {
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ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
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EXPECT_FALSE(exception_or_vector.result().empty());
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// Moving the result should clear the source.
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std::vector<int> moved = std::move(exception_or_vector).result();
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EXPECT_FALSE(moved.empty());
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}
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TEST(ExceptionOr, Result_Move_Const) {
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const ExceptionOr<std::vector<int>> exception_or_vector({1, 2, 3});
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EXPECT_FALSE(exception_or_vector.result().empty());
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// Moving const rvalue reference will result in a copy.
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std::vector<int> moved = std::move(exception_or_vector).result();
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EXPECT_FALSE(moved.empty());
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}
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TEST(ExceptionOr, ExplicitConversionWorks) {
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class A {
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public:
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A() = default;
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};
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class B {
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public:
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B() = default;
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explicit B(A) {}
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};
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ExceptionOr<A> a(A{});
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ExceptionOr<B> b(a);
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EXPECT_TRUE(a.ok());
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EXPECT_TRUE(b.ok());
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}
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TEST(ExceptionOr, ExplicitConversionFailsToCompile) {
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class A {
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public:
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A() = default;
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};
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class B {
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public:
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B() = default;
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};
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ExceptionOr<A> a(A{});
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EXPECT_NON_COMPILE("no matching constructor", { ExceptionOr<B> b(a); });
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}
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TEST(ExceptionOr, BoolType) {
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EXPECT_TRUE(ExceptionOr<bool>(true));
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EXPECT_TRUE(ExceptionOr<bool>(true).GetResult());
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EXPECT_TRUE(ExceptionOr<bool>(true).result());
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EXPECT_TRUE(ExceptionOr<bool>(true).ok());
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EXPECT_EQ(ExceptionOr<bool>(true).exception(), Exception::kSuccess);
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EXPECT_TRUE(ExceptionOr<bool>(Exception::kSuccess));
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EXPECT_FALSE(ExceptionOr<bool>(false));
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EXPECT_FALSE(ExceptionOr<bool>(false).GetResult());
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EXPECT_FALSE(ExceptionOr<bool>(false).result());
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EXPECT_FALSE(ExceptionOr<bool>(false).ok());
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EXPECT_EQ(ExceptionOr<bool>(false).exception(), Exception::kFailed);
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EXPECT_FALSE(ExceptionOr<bool>());
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EXPECT_FALSE(ExceptionOr<bool>(Exception::kInterrupted));
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EXPECT_EQ(ExceptionOr<bool>(Exception::kInterrupted).exception(),
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Exception::kInterrupted);
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}
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} // namespace nearby
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