2 files changed, 118 insertions, 0 deletions

diff --git a/crates/libsyntax2/tests/testutils/Cargo.toml b/crates/libsyntax2/tests/testutils/Cargo.toml
new file mode 100644
index 000000000..53b20f17b
--- /dev/null
+++ b/crates/libsyntax2/tests/testutils/Cargo.toml
@@ -0,0 +1,7 @@
+[package]
+name = "testutils"
+version = "0.1.0"
+authors = ["Aleksey Kladov <[email protected]>"]
+
+[dependencies]
+difference = "2.0.0"
diff --git a/crates/libsyntax2/tests/testutils/src/lib.rs b/crates/libsyntax2/tests/testutils/src/lib.rs
new file mode 100644
index 000000000..39c821661
--- /dev/null
+++ b/crates/libsyntax2/tests/testutils/src/lib.rs
@@ -0,0 +1,111 @@
+extern crate difference;
+
+use std::{
+    fs,
+    path::{Path, PathBuf},
+};
+
+use difference::Changeset;
+
+/// Read file and normalize newlines.
+///
+/// `rustc` seems to always normalize `\r\n` newlines to `\n`:
+///
+/// ```
+/// let s = "
+/// ";
+/// assert_eq!(s.as_bytes(), &[10]);
+/// ```
+///
+/// so this should always be correct.
+fn read_text(path: &Path) -> String {
+    fs::read_to_string(path).unwrap().replace("\r\n", "\n")
+}
+
+pub fn dir_tests<F>(paths: &[&str], f: F)
+where
+    F: Fn(&str) -> String,
+{
+    for path in collect_tests(paths) {
+        let input_code = read_text(&path);
+        let parse_tree = f(&input_code);
+        let path = path.with_extension("txt");
+        if !path.exists() {
+            println!("\nfile: {}", path.display());
+            println!("No .txt file with expected result, creating...\n");
+            println!("{}\n{}", input_code, parse_tree);
+            fs::write(&path, parse_tree).unwrap();
+            panic!("No expected result")
+        }
+        let expected = read_text(&path);
+        let expected = expected.as_str();
+        let parse_tree = parse_tree.as_str();
+        assert_equal_text(expected, parse_tree, &path);
+    }
+}
+
+fn assert_equal_text(expected: &str, actual: &str, path: &Path) {
+    if expected != actual {
+        print_difference(expected, actual, path)
+    }
+}
+
+fn collect_tests(paths: &[&str]) -> Vec<PathBuf> {
+    paths
+        .iter()
+        .flat_map(|path| {
+            let path = test_data_dir().join(path);
+            test_from_dir(&path).into_iter()
+        })
+        .collect()
+}
+
+fn test_from_dir(dir: &Path) -> Vec<PathBuf> {
+    let mut acc = Vec::new();
+    for file in fs::read_dir(&dir).unwrap() {
+        let file = file.unwrap();
+        let path = file.path();
+        if path.extension().unwrap_or_default() == "rs" {
+            acc.push(path);
+        }
+    }
+    acc.sort();
+    acc
+}
+
+const REWRITE: bool = false;
+
+fn print_difference(expected: &str, actual: &str, path: &Path) {
+    let dir = project_dir();
+    let path = path.strip_prefix(&dir).unwrap_or_else(|_| path);
+    if expected.trim() == actual.trim() {
+        println!("whitespace difference, rewriting");
+        println!("file: {}\n", path.display());
+        fs::write(path, actual).unwrap();
+        return;
+    }
+    if REWRITE {
+        println!("rewriting {}", path.display());
+        fs::write(path, actual).unwrap();
+        return;
+    }
+    let changeset = Changeset::new(actual, expected, "\n");
+    println!("Expected:\n{}\n\nActual:\n{}\n", expected, actual);
+    print!("{}", changeset);
+    println!("file: {}\n", path.display());
+    panic!("Comparison failed")
+}
+
+fn project_dir() -> PathBuf {
+    let dir = env!("CARGO_MANIFEST_DIR");
+    PathBuf::from(dir)
+        .parent()
+        .unwrap()
+        .parent()
+        .unwrap()
+        .to_owned()
+}
+
+fn test_data_dir() -> PathBuf {
+    project_dir().join("tests/data")
+}