zig/test/behavior/struct.zig

const std = @import("std");
const builtin = @import("builtin");
const native_endian = builtin.target.cpu.arch.endian();
const expect = std.testing.expect;
const expectEqual = std.testing.expectEqual;
const expectEqualSlices = std.testing.expectEqualSlices;
const maxInt = std.math.maxInt;

const StructWithNoFields = struct {
    fn add(a: i32, b: i32) i32 {
        return a + b;
    }
};

test "call struct static method" {
    const result = StructWithNoFields.add(3, 4);
    try expect(result == 7);
}

const should_be_11 = StructWithNoFields.add(5, 6);

test "invoke static method in global scope" {
    try expect(should_be_11 == 11);
}

const empty_global_instance = StructWithNoFields{};

test "return empty struct instance" {
    _ = returnEmptyStructInstance();
}
fn returnEmptyStructInstance() StructWithNoFields {
    return empty_global_instance;
}

const StructFoo = struct {
    a: i32,
    b: bool,
    c: f32,
};
test "structs" {
    var foo: StructFoo = undefined;
    @memset(@ptrCast([*]u8, &foo), 0, @sizeOf(StructFoo));
    foo.a += 1;
    foo.b = foo.a == 1;
    try testFoo(foo);
    testMutation(&foo);
    try expect(foo.c == 100);
}
fn testFoo(foo: StructFoo) !void {
    try expect(foo.b);
}
fn testMutation(foo: *StructFoo) void {
    foo.c = 100;
}

test "struct byval assign" {
    var foo1: StructFoo = undefined;
    var foo2: StructFoo = undefined;

    foo1.a = 1234;
    foo2.a = 0;
    try expect(foo2.a == 0);
    foo2 = foo1;
    try expect(foo2.a == 1234);
}

const Node = struct {
    val: Val,
    next: *Node,
};

const Val = struct {
    x: i32,
};

test "struct initializer" {
    const val = Val{ .x = 42 };
    try expect(val.x == 42);
}

const MemberFnTestFoo = struct {
    x: i32,
    fn member(foo: MemberFnTestFoo) i32 {
        return foo.x;
    }
};

test "call member function directly" {
    const instance = MemberFnTestFoo{ .x = 1234 };
    const result = MemberFnTestFoo.member(instance);
    try expect(result == 1234);
}

test "struct point to self" {
    var root: Node = undefined;
    root.val.x = 1;

    var node: Node = undefined;
    node.next = &root;
    node.val.x = 2;

    root.next = &node;

    try expect(node.next.next.next.val.x == 1);
}

test "void struct fields" {
    const foo = VoidStructFieldsFoo{
        .a = void{},
        .b = 1,
        .c = void{},
    };
    try expect(foo.b == 1);
    try expect(@sizeOf(VoidStructFieldsFoo) == 4);
}
const VoidStructFieldsFoo = struct {
    a: void,
    b: i32,
    c: void,
};

test "member functions" {
    const r = MemberFnRand{ .seed = 1234 };
    try expect(r.getSeed() == 1234);
}
const MemberFnRand = struct {
    seed: u32,
    pub fn getSeed(r: *const MemberFnRand) u32 {
        return r.seed;
    }
};

test "return struct byval from function" {
    const bar = makeBar2(1234, 5678);
    try expect(bar.y == 5678);
}
const Bar = struct {
    x: i32,
    y: i32,
};
fn makeBar2(x: i32, y: i32) Bar {
    return Bar{
        .x = x,
        .y = y,
    };
}