75 lines
1.8 KiB
C++
75 lines
1.8 KiB
C++
#include <gmock/gmock.h>
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#include "tools/Lazy.h"
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using namespace testing;
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// Not copyable, no default constructor, movable
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struct Foo {
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const int value;
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Foo(int value) : value(value) {}
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Foo() = delete;
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Foo(const Foo&) = delete;
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Foo& operator=(const Foo&) = delete;
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Foo(Foo&&) = default;
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Foo& operator=(Foo&&) = default;
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};
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TEST(Lazy, basicUsage) {
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bool lambdaCalled = false;
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Lazy<Foo> lazy([&lambdaCalled] { lambdaCalled = true; return Foo(42); });
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EXPECT_FALSE(lambdaCalled);
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EXPECT_FALSE(static_cast<bool>(lazy));
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EXPECT_EQ(42, (*lazy).value);
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EXPECT_EQ(42, lazy.value().value);
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EXPECT_EQ(42, lazy->value);
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EXPECT_TRUE(lambdaCalled);
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EXPECT_TRUE(static_cast<bool>(lazy));
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}
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TEST(Lazy, constUsage) {
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bool lambdaCalled = false;
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const Lazy<Foo> lazy([&lambdaCalled] { lambdaCalled = true; return Foo(42); });
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EXPECT_FALSE(lambdaCalled);
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EXPECT_FALSE(static_cast<bool>(lazy));
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EXPECT_EQ(42, (*lazy).value);
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EXPECT_EQ(42, lazy.value().value);
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EXPECT_EQ(42, lazy->value);
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EXPECT_TRUE(lambdaCalled);
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EXPECT_TRUE(static_cast<bool>(lazy));
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}
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TEST(Lazy, copying) {
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Lazy<Foo> a;
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int counter = 0;
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const auto createValue = [&] { return counter++; };
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Lazy<Foo> b(createValue);
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a = b;
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EXPECT_EQ(0, counter);
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EXPECT_FALSE(static_cast<bool>(a));
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EXPECT_FALSE(static_cast<bool>(b));
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EXPECT_EQ(0, a->value);
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EXPECT_EQ(1, counter);
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EXPECT_TRUE(static_cast<bool>(a));
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EXPECT_TRUE(static_cast<bool>(b));
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EXPECT_EQ(0, b->value);
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Lazy<Foo> c(createValue);
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EXPECT_EQ(1, c->value);
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}
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using Expensive = Foo;
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#define member value;
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TEST(Lazy, demo) {
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// Constructor takes function
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Lazy<Expensive> lazy([] { return Expensive(42); });
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// Multiple ways to access value
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Expensive& a = *lazy;
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Expensive& b = lazy.value();
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auto c = lazy->member;
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// Check if initialized
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if (lazy) { /* ... */ }
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} |