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                    <h1 class="menu-title">The bindgen User Guide</h1>

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                        <h1><a class="header" href="#write-a-sanity-test" id="write-a-sanity-test">Write a Sanity Test</a></h1>
<p>Finally, to tie everything together, let's write a sanity test that round trips
some text through compression and decompression, and then asserts that it came
back out the same as it went in. This is a little wordy using the raw FFI
bindings, but hopefully we wouldn't usually ask people to do this, we'd provide
a nice Rust-y API on top of the raw FFI bindings for them. However, since this
is for testing the bindings directly, our sanity test will use the bindings
directly.</p>
<p>The test data I'm round tripping are some Futurama quotes I got off the internet
and put in the <code>futurama-quotes.txt</code> file, which is read into a <code>&amp;'static str</code>
at compile time via the <code>include_str!(&quot;../futurama-quotes.txt&quot;)</code> macro
invocation.</p>
<p>Without further ado, here is the test, which should be appended to the bottom of
our <code>src/lib.rs</code> file:</p>
<pre><pre class="playground"><code class="language-rust">
<span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>#[cfg(test)]
mod tests {
    use super::*;
    use std::mem;

    #[test]
    fn round_trip_compression_decompression() {
        unsafe {
            let input = include_str!(&quot;../futurama-quotes.txt&quot;).as_bytes();
            let mut compressed_output: Vec&lt;u8&gt; = vec![0; input.len()];
            let mut decompressed_output: Vec&lt;u8&gt; = vec![0; input.len()];

            // Construct a compression stream.
            let mut stream: bz_stream = mem::zeroed();
            let result = BZ2_bzCompressInit(&amp;mut stream as *mut _,
                                            1,   // 1 x 100000 block size
                                            4,   // verbosity (4 = most verbose)
                                            0);  // default work factor
            match result {
                r if r == (BZ_CONFIG_ERROR as _) =&gt; panic!(&quot;BZ_CONFIG_ERROR&quot;),
                r if r == (BZ_PARAM_ERROR as _) =&gt; panic!(&quot;BZ_PARAM_ERROR&quot;),
                r if r == (BZ_MEM_ERROR as _) =&gt; panic!(&quot;BZ_MEM_ERROR&quot;),
                r if r == (BZ_OK as _) =&gt; {},
                r =&gt; panic!(&quot;Unknown return value = {}&quot;, r),
            }

            // Compress `input` into `compressed_output`.
            stream.next_in = input.as_ptr() as *mut _;
            stream.avail_in = input.len() as _;
            stream.next_out = compressed_output.as_mut_ptr() as *mut _;
            stream.avail_out = compressed_output.len() as _;
            let result = BZ2_bzCompress(&amp;mut stream as *mut _, BZ_FINISH as _);
            match result {
                r if r == (BZ_RUN_OK as _) =&gt; panic!(&quot;BZ_RUN_OK&quot;),
                r if r == (BZ_FLUSH_OK as _) =&gt; panic!(&quot;BZ_FLUSH_OK&quot;),
                r if r == (BZ_FINISH_OK as _) =&gt; panic!(&quot;BZ_FINISH_OK&quot;),
                r if r == (BZ_SEQUENCE_ERROR as _) =&gt; panic!(&quot;BZ_SEQUENCE_ERROR&quot;),
                r if r == (BZ_STREAM_END as _) =&gt; {},
                r =&gt; panic!(&quot;Unknown return value = {}&quot;, r),
            }

            // Finish the compression stream.
            let result = BZ2_bzCompressEnd(&amp;mut stream as *mut _);
            match result {
                r if r == (BZ_PARAM_ERROR as _) =&gt; panic!(&quot;BZ_PARAM_ERROR&quot;),
                r if r == (BZ_OK as _) =&gt; {},
                r =&gt; panic!(&quot;Unknown return value = {}&quot;, r),
            }

            // Construct a decompression stream.
            let mut stream: bz_stream = mem::zeroed();
            let result = BZ2_bzDecompressInit(&amp;mut stream as *mut _,
                                              4,   // verbosity (4 = most verbose)
                                              0);  // default small factor
            match result {
                r if r == (BZ_CONFIG_ERROR as _) =&gt; panic!(&quot;BZ_CONFIG_ERROR&quot;),
                r if r == (BZ_PARAM_ERROR as _) =&gt; panic!(&quot;BZ_PARAM_ERROR&quot;),
                r if r == (BZ_MEM_ERROR as _) =&gt; panic!(&quot;BZ_MEM_ERROR&quot;),
                r if r == (BZ_OK as _) =&gt; {},
                r =&gt; panic!(&quot;Unknown return value = {}&quot;, r),
            }

            // Decompress `compressed_output` into `decompressed_output`.
            stream.next_in = compressed_output.as_ptr() as *mut _;
            stream.avail_in = compressed_output.len() as _;
            stream.next_out = decompressed_output.as_mut_ptr() as *mut _;
            stream.avail_out = decompressed_output.len() as _;
            let result = BZ2_bzDecompress(&amp;mut stream as *mut _);
            match result {
                r if r == (BZ_PARAM_ERROR as _) =&gt; panic!(&quot;BZ_PARAM_ERROR&quot;),
                r if r == (BZ_DATA_ERROR as _) =&gt; panic!(&quot;BZ_DATA_ERROR&quot;),
                r if r == (BZ_DATA_ERROR_MAGIC as _) =&gt; panic!(&quot;BZ_DATA_ERROR&quot;),
                r if r == (BZ_MEM_ERROR as _) =&gt; panic!(&quot;BZ_MEM_ERROR&quot;),
                r if r == (BZ_OK as _) =&gt; panic!(&quot;BZ_OK&quot;),
                r if r == (BZ_STREAM_END as _) =&gt; {},
                r =&gt; panic!(&quot;Unknown return value = {}&quot;, r),
            }

            // Close the decompression stream.
            let result = BZ2_bzDecompressEnd(&amp;mut stream as *mut _);
            match result {
                r if r == (BZ_PARAM_ERROR as _) =&gt; panic!(&quot;BZ_PARAM_ERROR&quot;),
                r if r == (BZ_OK as _) =&gt; {},
                r =&gt; panic!(&quot;Unknown return value = {}&quot;, r),
            }

            assert_eq!(input, &amp;decompressed_output[..]);
        }
    }
}
<span class="boring">}
</span></code></pre></pre>
<p>Now let's run <code>cargo test</code> again and verify that everything is linking and binding
properly!</p>
<pre><code class="language-bash">$ cargo test
   Compiling bindgen-tutorial-bzip2-sys v0.1.0
    Finished debug [unoptimized + debuginfo] target(s) in 0.54 secs
     Running target/debug/deps/bindgen_tutorial_bzip2_sys-1c5626bbc4401c3a

running 15 tests
test bindgen_test_layout___darwin_pthread_handler_rec ... ok
test bindgen_test_layout___sFILE ... ok
test bindgen_test_layout___sbuf ... ok
test bindgen_test_layout__bindgen_ty_1 ... ok
test bindgen_test_layout__bindgen_ty_2 ... ok
test bindgen_test_layout__opaque_pthread_attr_t ... ok
test bindgen_test_layout__opaque_pthread_cond_t ... ok
test bindgen_test_layout__opaque_pthread_condattr_t ... ok
test bindgen_test_layout__opaque_pthread_mutex_t ... ok
test bindgen_test_layout__opaque_pthread_mutexattr_t ... ok
test bindgen_test_layout__opaque_pthread_once_t ... ok
test bindgen_test_layout__opaque_pthread_rwlock_t ... ok
test bindgen_test_layout__opaque_pthread_rwlockattr_t ... ok
test bindgen_test_layout__opaque_pthread_t ... ok
    block 1: crc = 0x47bfca17, combined CRC = 0x47bfca17, size = 2857
        bucket sorting ...
        depth      1 has   2849 unresolved strings
        depth      2 has   2702 unresolved strings
        depth      4 has   1508 unresolved strings
        depth      8 has    538 unresolved strings
        depth     16 has    148 unresolved strings
        depth     32 has      0 unresolved strings
        reconstructing block ...
      2857 in block, 2221 after MTF &amp; 1-2 coding, 61+2 syms in use
      initial group 5, [0 .. 1], has 570 syms (25.7%)
      initial group 4, [2 .. 2], has 256 syms (11.5%)
      initial group 3, [3 .. 6], has 554 syms (24.9%)
      initial group 2, [7 .. 12], has 372 syms (16.7%)
      initial group 1, [13 .. 62], has 469 syms (21.1%)
      pass 1: size is 2743, grp uses are 13 6 15 0 11
      pass 2: size is 1216, grp uses are 13 7 15 0 10
      pass 3: size is 1214, grp uses are 13 8 14 0 10
      pass 4: size is 1213, grp uses are 13 9 13 0 10
      bytes: mapping 19, selectors 17, code lengths 79, codes 1213
    final combined CRC = 0x47bfca17

    [1: huff+mtf rt+rld {0x47bfca17, 0x47bfca17}]
    combined CRCs: stored = 0x47bfca17, computed = 0x47bfca17
test tests::round_trip_compression_decompression ... ok

test result: ok. 15 passed; 0 failed; 0 ignored; 0 measured

   Doc-tests bindgen-tutorial-bzip2-sys

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured
</code></pre>

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