Bring back the integration tests

[orhun]

Describe the bug

The "run" test was removed in #28 and we should add it back!

To reproduce

Add the following test:

test "run" {
    const allocator = std.testing.allocator;
    var buffer = std.ArrayList(u8).init(allocator);
    const output = buffer.writer();
    try run(allocator, output);
    const result = buffer.toOwnedSlice();
    defer allocator.free(result);
    try std.testing.expectEqualStrings(
        \\Reading 96 bytes from /dev/urandom
        \\Saving to output.wav
        \\
    , result);
}

And run zig build test --summary all

$ zig build test --summary all
test
└─ run main-tests
   └─ zig test main-tests Debug native 1 errors
src/main.zig:112:7: error: expected type '[]const u8', found 'error{OutOfMemory}![]u8'
    , result);
      ^~~~~~
/usr/lib/zig/std/testing.zig:602:57: note: parameter type declared here
pub fn expectEqualStrings(expected: []const u8, actual: []const u8) !void {
                                                        ^~~~~~~~~~
error: the following command failed with 1 compilation errors:
/usr/bin/zig test -ODebug --dep clap --dep file --dep gen --dep wav --dep build_options -Mroot=/home/orhun/gh/linuxwave/src/main.zig -Mclap=/home/orhun/.cache/zig/p/122062d301a203d003547b414237229b09a7980095061697349f8bef41be9c30266b/clap.zig -Mfile=/home/orhun/gh/linuxwave/src/file.zig -Mgen=/home/orhun/gh/linuxwave/src/gen.zig -Mwav=/home/orhun/gh/linuxwave/src/wav.zig -Mbuild_options=/home/orhun/gh/linuxwave/.zig-cache/c/39ab14edd4b808fc84a6290cbce71a92/options.zig --cache-dir /home/orhun/gh/linuxwave/.zig-cache --global-cache-dir /home/orhun/.cache/zig --name main-tests --listen=-
Build Summary: 7/10 steps succeeded; 1 failed
test transitive failure
├─ run file-tests cached
│  └─ zig test file-tests Debug native cached 24ms MaxRSS:43M
│     └─ options cached
├─ run gen-tests cached
│  └─ zig test gen-tests Debug native cached 26ms MaxRSS:43M
│     └─ options (reused)
├─ run wav-tests cached
│  └─ zig test wav-tests Debug native cached 24ms MaxRSS:43M
│     └─ options (reused)
└─ run main-tests transitive failure
   └─ zig test main-tests Debug native 1 errors
      └─ options (reused)
error: the following build command failed with exit code 1:
/home/orhun/gh/linuxwave/.zig-cache/o/afb7cc6a9f9ac5c36087ee47fee4d7b5/build /usr/bin/zig /home/orhun/gh/linuxwave /home/orhun/gh/linuxwave/.zig-cache /home/orhun/.cache/zig --seed 0x437fe8a7 -Za0187a4813cc29b8 test --summary all

Expected behavior

Passed tests.

Software information

• Operating system: arch btw
• Zig version: 0.13
• Project version: main

Additional context

Shoutout to @tranzystorekk