Hook the integration tests into rust's test framework.

Instead of using a hacked-together shell script, use rust's test framework to do the comparison.

build.rs

@@ -0,0 +1,58 @@
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::Path;
+use walkdir::WalkDir;
+
+fn main() {
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let destination = Path::new(&out_dir).join("tests.rs");
+    let mut test_file = File::create(&destination).unwrap();
+
+    write_header(&mut test_file);
+
+    let test_files = WalkDir::new("org_mode_samples")
+        .into_iter()
+        .filter(|e| match e {
+            Ok(dir_entry) => {
+                dir_entry.file_type().is_file()
+                    && Path::new(dir_entry.file_name())
+                        .extension()
+                        .map(|ext| ext.to_ascii_lowercase() == "org")
+                        .unwrap_or(false)
+            }
+            Err(_) => true,
+        }).collect::<Result<Vec<_>, _>>().unwrap();
+    for test in test_files {
+        write_test(&mut test_file, &test);
+    }
+
+}
+
+fn write_test(test_file: &mut File, test: &walkdir::DirEntry) {
+    let test_name = test.path().strip_prefix("org_mode_samples/").expect("Paths should be under org_mode_samples/").to_string_lossy().to_lowercase().strip_suffix(".org").expect("Should have .org extension").replace("/", "_");
+
+
+    write!(
+        test_file,
+        include_str!("./tests/test_template"),
+        name = test_name,
+        path = test.path().display()
+    )
+    .unwrap();
+}
+
+fn write_header(test_file: &mut File) {
+    write!(
+        test_file,
+        r#"
+#[feature(exit_status_error)]
+use organic::compare_document;
+use organic::document;
+use organic::emacs_parse_org_document;
+use organic::sexp;
+
+"#
+    )
+    .unwrap();
+}