1 files changed, 99 insertions, 1 deletions

diff --git a/crates/ra_syntax/src/tests.rs b/crates/ra_syntax/src/tests.rs
index 959967b79..f14f23628 100644
--- a/crates/ra_syntax/src/tests.rs
+++ b/crates/ra_syntax/src/tests.rs
@@ -1,9 +1,11 @@
 use std::{
+    env,
     fmt::Write,
+    fs,
     path::{Component, Path, PathBuf},
 };
 
-use test_utils::{collect_rust_files, dir_tests, project_dir, read_text};
+use test_utils::{assert_eq_text, project_dir};
 
 use crate::{fuzz, tokenize, SourceFile, SyntaxError, TextRange, TextSize, Token};
 
@@ -200,3 +202,99 @@ where
         }
     });
 }
+
+/// Calls callback `f` with input code and file paths for each `.rs` file in `test_data_dir`
+/// subdirectories defined by `paths`.
+///
+/// If the content of the matching output file differs from the output of `f()`
+/// the test will fail.
+///
+/// If there is no matching output file it will be created and filled with the
+/// output of `f()`, but the test will fail.
+fn dir_tests<F>(test_data_dir: &Path, paths: &[&str], outfile_extension: &str, f: F)
+where
+    F: Fn(&str, &Path) -> String,
+{
+    for (path, input_code) in collect_rust_files(test_data_dir, paths) {
+        let actual = f(&input_code, &path);
+        let path = path.with_extension(outfile_extension);
+        if !path.exists() {
+            println!("\nfile: {}", path.display());
+            println!("No .txt file with expected result, creating...\n");
+            println!("{}\n{}", input_code, actual);
+            fs::write(&path, &actual).unwrap();
+            panic!("No expected result");
+        }
+        let expected = read_text(&path);
+        assert_equal_text(&expected, &actual, &path);
+    }
+}
+
+/// Collects all `.rs` files from `dir` subdirectories defined by `paths`.
+fn collect_rust_files(root_dir: &Path, paths: &[&str]) -> Vec<(PathBuf, String)> {
+    paths
+        .iter()
+        .flat_map(|path| {
+            let path = root_dir.to_owned().join(path);
+            rust_files_in_dir(&path).into_iter()
+        })
+        .map(|path| {
+            let text = read_text(&path);
+            (path, text)
+        })
+        .collect()
+}
+
+/// Collects paths to all `.rs` files from `dir` in a sorted `Vec<PathBuf>`.
+fn rust_files_in_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
+}
+
+/// Asserts that `expected` and `actual` strings are equal. If they differ only
+/// in trailing or leading whitespace the test won't fail and
+/// the contents of `actual` will be written to the file located at `path`.
+fn assert_equal_text(expected: &str, actual: &str, path: &Path) {
+    if expected == actual {
+        return;
+    }
+    let dir = project_dir();
+    let pretty_path = path.strip_prefix(&dir).unwrap_or_else(|_| path);
+    if expected.trim() == actual.trim() {
+        println!("whitespace difference, rewriting");
+        println!("file: {}\n", pretty_path.display());
+        fs::write(path, actual).unwrap();
+        return;
+    }
+    if env::var("UPDATE_EXPECTATIONS").is_ok() {
+        println!("rewriting {}", pretty_path.display());
+        fs::write(path, actual).unwrap();
+        return;
+    }
+    assert_eq_text!(expected, actual, "file: {}", pretty_path.display());
+}
+
+/// 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_or_else(|_| panic!("File at {:?} should be valid", path))
+        .replace("\r\n", "\n")
+}