Generate a separate test function for every header

- Header tests can now be run selectively, e.g. `cargo test union`
  will test all headers with 'union' in the file name.
- The list of test functions is generated by `build.rs`, so never
  needs to be updated.
- Clever approach suggested by @fitzgen.

Author: jdub

libbindgen/build.rs

@@ -1,10 +1,9 @@
 mod codegen {
     extern crate quasi_codegen;
     use std::path::Path;
-    use std::env;
 
     pub fn main() {
-        let out_dir = env::var_os("OUT_DIR").unwrap();
+        let out_dir = Path::new(env!("OUT_DIR"));
         let src = Path::new("src/codegen/mod.rs");
         let dst = Path::new(&out_dir).join("codegen.rs");
 
@@ -14,6 +13,42 @@ mod codegen {
     }
 }
 
+mod testgen {
+    use std::char;
+    use std::ffi::OsStr;
+    use std::fs::{self, File};
+    use std::io::Write;
+    use std::path::Path;
+
+    pub fn main() {
+        let out_dir = Path::new(env!("OUT_DIR"));
+        let mut dst = File::create(Path::new(&out_dir).join("tests.rs")).unwrap();
+
+        let manifest_dir = Path::new(env!("CARGO_MANIFEST_DIR"));
+        let headers_dir = manifest_dir.join("tests").join("headers");
+
+        let entries = fs::read_dir(headers_dir)
+            .expect("Couldn't read headers dir")
+            .map(|result| result.expect("Couldn't read header file"));
+
+        for entry in entries {
+            match entry.path().extension().and_then(OsStr::to_str) {
+                Some("h") | Some("hpp") => {
+                    let func = entry.file_name().to_str().unwrap()
+                        .replace(|c| !char::is_alphanumeric(c), "_")
+                        .replace("__", "_")
+                        .to_lowercase();
+                    let _ = writeln!(dst, "test_header!(header_{}, {:?});",
+                        func, entry.path());
+                }
+                _ => {}
+            }
+        }
+        let _ = dst.flush();
+    }
+}
+
 fn main() {
     codegen::main();
+    testgen::main();
 }

libbindgen/tests/tests.rs

@@ -6,10 +6,9 @@ extern crate libbindgen;
 extern crate log;
 extern crate shlex;
 
-use std::env;
 use std::fs;
 use std::io::{BufRead, BufReader, Error, ErrorKind, Read};
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 
 #[path="../../src/options.rs"]
 mod options;
@@ -93,46 +92,17 @@ fn create_bindgen_builder(header: &PathBuf)
     builder_from_flags(args).map(|(builder, _)| builder.no_unstable_rust())
 }
 
-#[test]
-fn run_bindgen_tests() {
-    log::set_logger(|max_log_level| {
-            use env_logger::Logger;
-            let env_logger = Logger::new();
-            max_log_level.set(env_logger.filter());
-            Box::new(env_logger)
-        })
-        .expect("Failed to set logger.");
-
-    let manifest_env = env::var("CARGO_MANIFEST_DIR")
-        .expect("CARGO_MANIFEST_DIR not set!");
-    let manifest_dir = Path::new(&manifest_env);
-    let headers_dir = manifest_dir.join("tests").join("headers");
-
-    let entries = fs::read_dir(&headers_dir)
-        .expect("Couldn't read headers dir")
-        .map(|result| result.expect("Couldn't read header file"));
-
-    let headers: Vec<_> = entries.filter_map(|entry| {
-            match entry.path().extension().and_then(|s| s.to_str()) {
-                Some("h") | Some("hpp") => Some(entry.path()),
-                _ => None,
-            }
-        })
-        .collect();
-
-    let failures: Vec<_> = headers.iter()
-        .filter_map(|header| {
-            create_bindgen_builder(header)
-                .and_then(|builder| compare_generated_header(header, builder))
-                .err()
-        })
-        .collect();
-
-    let num_failures = failures.len();
-
-    if num_failures > 0 {
-        panic!("{} test{} failed!",
-               num_failures,
-               if num_failures > 1 {"s"} else {""});
-    }
+macro_rules! test_header {
+    ($function:ident, $header:expr) => (
+        #[test]
+        fn $function() {
+            let header = PathBuf::from($header);
+            let _ = create_bindgen_builder(&header)
+                .and_then(|builder| compare_generated_header(&header, builder))
+                .map_err(|err| panic!(format!("{}", err)) );
+        }
+    )
 }
+
+// This file is generated by build.rs
+include!(concat!(env!("OUT_DIR"), "/tests.rs"));