Ensure that we run layout tests from libclang version-specific expectations

This adds a build.rs to generate

    #[path="$FILE"]
    mod $FILE_AS_IDENT;

for each $FILE in our libclang version-specific directories. We need to do this
to get those files' layout tests to run because cargo doesn't automatically pick
up tests in subdirectories.

2 files changed, 61 insertions, 0 deletions

diff --git a/tests/expectations/build.rs b/tests/expectations/build.rs
new file mode 100644
index 00000000..0727ce51
--- /dev/null
+++ b/tests/expectations/build.rs
@@ -0,0 +1,60 @@
+//! Generate a module with a custom `#[path=...]` for each of the files in our
+//! libclang version-specific test expectations so that they get their layout
+//! tests run. We need to do this because cargo doesn't automatically detect
+//! tests subdirectories.
+
+use std::env;
+use std::fs;
+use std::io::Write;
+use std::path::Path;
+
+const LIBCLANG_VERSION_DIRS: &'static [&'static str] =
+    &["libclang-3.8", "libclang-3.9", "libclang-4"];
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+
+    let mut test_string = String::new();
+
+    for dir in LIBCLANG_VERSION_DIRS {
+        let dir = Path::new(&env::var_os("CARGO_MANIFEST_DIR").unwrap())
+            .join("tests")
+            .join(dir);
+
+        println!("cargo:rerun-if-changed={}", dir.display());
+
+        for entry in fs::read_dir(dir).unwrap() {
+            let entry = entry.unwrap();
+            let path = entry.path();
+            let path = path.canonicalize().unwrap_or_else(|_| path.into());
+            if path.extension().map(|e| e.to_string_lossy()) != Some("rs".into()) {
+                continue;
+            }
+
+            println!("cargo:rerun-if-changed={}", path.display());
+
+            let module_name: String = path.display()
+                .to_string()
+                .chars()
+                .map(|c| match c {
+                    'a'...'z' | 'A'...'Z' | '0'...'9' => c,
+                    _ => '_',
+                })
+                .collect();
+
+            test_string.push_str(&format!(
+                r###"
+#[path = "{}"]
+mod {};
+"###,
+                path.display(),
+                module_name,
+            ));
+        }
+    }
+
+    let out_path = Path::new(&env::var_os("OUT_DIR").unwrap())
+        .join("libclang_version_specific_generated_tests.rs");
+    let mut test_file = fs::File::create(out_path).unwrap();
+    test_file.write_all(test_string.as_bytes()).unwrap();
+}
diff --git a/tests/expectations/tests/libclang_version_specific_generated_tests.rs b/tests/expectations/tests/libclang_version_specific_generated_tests.rs
new file mode 100644
index 00000000..93cf0d47
--- /dev/null
+++ b/tests/expectations/tests/libclang_version_specific_generated_tests.rs
@@ -0,0 +1 @@
+include!(concat!(env!("OUT_DIR"), "/libclang_version_specific_generated_tests.rs"));