Add testing infrastructure for slang

.clang-format

@@ -0,0 +1,18 @@
+---
+Language:        Cpp
+BasedOnStyle:    LLVM
+
+# 4 spaces everywhere
+IndentWidth:     4
+TabWidth:        4
+UseTab:          Never
+ContinuationIndentWidth: 4
+
+# Modern C++ style
+Standard:        c++20
+ColumnLimit:     120
+PointerAlignment: Left
+
+# Organize includes
+SortIncludes:    true
+IncludeBlocks:   Regroup

.clangd

@@ -0,0 +1,15 @@
+If:
+  PathMatch: (^|.*/)crates/bender-slang/cpp/.*\.(h|hpp|hh|c|cc|cpp|cxx)$
+CompileFlags:
+  Add:
+    - -std=c++20
+    - -fno-cxx-modules
+    - -I.
+    - -I../../../crates
+    - -I../vendor/slang/include
+    - -I../vendor/slang/external
+    - -I../../../target/slang-generated-include
+    - -I../../../target/cxxbridge
+    - -DSLANG_USE_MIMALLOC=1
+    - -DSLANG_USE_THREADS=1
+    - -DSLANG_BOOST_SINGLE_HEADER=1

.github/workflows/ci.yml

@@ -4,7 +4,6 @@ on:
   push:
     branches: [master]
   pull_request:
-    branches: [master]
   workflow_dispatch:
 
 jobs:

.gitignore

@@ -1,6 +1,9 @@
-.*
-!/.ci/
-!.git*
-!.travis.yml
-/target
-/tests/tmp
+# Cargo build files
+target
+
+# Temporary test files
+tests/**/tmp
+tests/**/.bender
+
+# clangd
+.cache/clangd

crates/bender-slang/build.rs

@@ -1,6 +1,37 @@
 // Copyright (c) 2025 ETH Zurich
 // Tim Fischer <fischeti@iis.ee.ethz.ch>
 
+#[cfg(unix)]
+// We create a symlink from the generated include directory to a stable location in the target directory
+// so that tools like clangd can find the headers without needing to know the exact OUT_DIR path.
+// This is purely for improving the development experience and is not necessary for the build itself.
+fn refresh_include_symlink(generated_include_dir: &std::path::Path) {
+    use std::ffi::OsStr;
+    use std::fs;
+    use std::os::unix::fs::symlink;
+    use std::path::PathBuf;
+
+    let Ok(out_dir) = std::env::var("OUT_DIR") else {
+        return;
+    };
+    let out_dir = PathBuf::from(out_dir);
+
+    let Some(target_root) = out_dir
+        .ancestors()
+        .find(|path| path.file_name() == Some(OsStr::new("target")))
+    else {
+        return;
+    };
+
+    let stable_link = target_root.join("slang-generated-include");
+    let _ = fs::remove_file(&stable_link);
+    let _ = fs::remove_dir_all(&stable_link);
+    let _ = symlink(generated_include_dir, &stable_link);
+}
+
+#[cfg(not(unix))]
+fn refresh_include_symlink(_generated_include_dir: &std::path::Path) {}
+
 fn main() {
     let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap();
     let target_env = std::env::var("CARGO_CFG_TARGET_ENV").unwrap();
@@ -64,6 +95,11 @@ fn main() {
     let dst = slang_lib.build();
     let lib_dir = dst.join("lib");
 
+    // Create a symlink for the generated include directory
+    if target_os == "linux" || target_os == "macos" {
+        refresh_include_symlink(&dst.join("include"));
+    }
+
     // Configure Linker to find Slang static library
     println!("cargo:rustc-link-search=native={}", lib_dir.display());
     println!("cargo:rustc-link-lib=static=svlang");

crates/bender-slang/cpp/slang_bridge.h

@@ -7,8 +7,9 @@
 #include "rust/cxx.h"
 #include "slang/diagnostics/DiagnosticEngine.h"
 #include "slang/diagnostics/TextDiagnosticClient.h"
-#include "slang/driver/Driver.h"
+#include "slang/parsing/Preprocessor.h"
 #include "slang/syntax/SyntaxTree.h"
+#include "slang/text/SourceManager.h"
 
 #include <cstddef>
 #include <cstdint>

crates/bender-slang/tests/basic.rs

@@ -0,0 +1,96 @@
+use std::path::PathBuf;
+
+fn fixture_path(rel: &str) -> String {
+    PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+        .join("../..")
+        .join("tests/pickle")
+        .join(rel)
+        .canonicalize()
+        .expect("valid fixture path")
+        .to_string_lossy()
+        .into_owned()
+}
+
+#[test]
+fn parse_valid_file_succeeds() {
+    let mut session = bender_slang::SlangSession::new();
+    let files = vec![fixture_path("src/top.sv")];
+    let includes = vec![fixture_path("include")];
+    let defines = vec![];
+    assert!(session.parse_group(&files, &includes, &defines).is_ok());
+    assert_eq!(session.tree_count(), 1);
+}
+
+#[test]
+fn parse_invalid_file_returns_parse_error() {
+    let mut session = bender_slang::SlangSession::new();
+    let files = vec![fixture_path("src/broken.sv")];
+    let includes = vec![];
+    let defines = vec![];
+    let result = session.parse_group(&files, &includes, &defines);
+
+    match result {
+        Err(bender_slang::SlangError::ParseGroup { .. }) => {}
+        Err(other) => panic!("expected SlangError::ParseGroup, got {other}"),
+        Ok(_) => panic!("expected parse to fail"),
+    }
+}
+
+#[test]
+fn rewriter_build_from_trees_is_repeatable() {
+    let mut session = bender_slang::SlangSession::new();
+    let files = vec![fixture_path("src/top.sv")];
+    let includes = vec![fixture_path("include")];
+    let defines = vec![];
+    session
+        .parse_group(&files, &includes, &defines)
+        .expect("parse should succeed");
+
+    let trees = session.all_trees().expect("tree collection should succeed");
+    let mut rewriter_once = bender_slang::SyntaxTreeRewriter::new();
+    rewriter_once.set_prefix("p_");
+    rewriter_once.set_suffix("_s");
+    let first_pass_trees: Vec<_> = trees
+        .iter()
+        .map(|t| rewriter_once.rewrite_declarations(t))
+        .collect();
+    let renamed_once = rewriter_once.rewrite_references(
+        first_pass_trees
+            .first()
+            .expect("one first-pass tree expected"),
+    );
+    assert!(
+        renamed_once
+            .display(bender_slang::SlangPrintOpts {
+                expand_macros: false,
+                include_directives: true,
+                include_comments: true,
+                squash_newlines: false,
+            })
+            .contains("module p_top_s (")
+    );
+
+    // Rebuilding with the same trees should remain stable.
+    let mut rewriter_twice = bender_slang::SyntaxTreeRewriter::new();
+    rewriter_twice.set_prefix("p_");
+    rewriter_twice.set_suffix("_s");
+    let first_pass_trees: Vec<_> = trees
+        .iter()
+        .map(|t| rewriter_twice.rewrite_declarations(t))
+        .collect();
+    let renamed_twice = rewriter_twice.rewrite_references(
+        first_pass_trees
+            .first()
+            .expect("one first-pass tree expected"),
+    );
+    assert!(
+        renamed_twice
+            .display(bender_slang::SlangPrintOpts {
+                expand_macros: false,
+                include_directives: true,
+                include_comments: true,
+                squash_newlines: false,
+            })
+            .contains("module p_top_s (")
+    );
+}

tests/cli_regression.rs

@@ -161,5 +161,8 @@ regression_tests! {
     packages:                       &["packages"],
     packages_graph:                 &["packages", "--graph"],
     packages_flat:                  &["packages", "--flat"],
+    // Enable once the golden binary is built with `slang` support.
+    // pickle_basic:                   &["pickle", "--target", "top"],
+    // pickle_top_trim:                &["pickle", "--target", "top", "--top", "top"],
 
 }