native test framework

LANGUAGE.md

@@ -18,6 +18,8 @@ roadmap and milestone history.
 - `hide` makes any named top-level declaration file-local; declarations are public by default,
   leading underscores are ordinary identifier characters, and imports are always file-local
 - relative `.h` imports as synthetic C header package namespaces
+- native `name test { ... }` declarations with implicit fallible-void results, plus anonymous
+  transitive `test import "..."` discovery used only by test builds
 - root `main` validation with trap executable recovery for missing or unusable entry points
 
 ### scalar, aggregate, and pointer types
@@ -180,6 +182,8 @@ as `math.divfloor(a, b)` resolve to ordinary functions.
 - `std/io` explicit `Io` capabilities, provider-bound `Reader`/`Writer` handles, existing-file open/close operations, allocation-free `write_all`, and comptime-expanded writer-first `print`; formatting supports natural `{}`, byte `{s}`, decimal `{d}`, integer `{b}` / `{o}` / `{x}` / `{X}`, byte-character `{c}`, scientific float `{e}`, and `{{` / `}}`, with malformed formats and incompatible tuple fields rejected at comptime
 - entry points are either `main func() ...` or `main func(init process.Init) ...`; `std/process.Init` carries startup capabilities, currently only `io`, while the system provider remains hidden inside `std/io`
 - `std/debug.print` is an allocation-free, failure-ignoring stderr escape hatch independent of `process.Init`
+- `std/testing` supplies fallible `expect` and expected-first `expect_equal`; direct calls through
+  an alias of exactly `@std/testing` receive compiler-injected source locations
 
 ### compiler behavior
 
@@ -188,6 +192,8 @@ as `math.divfloor(a, b)` resolve to ordinary functions.
 - static, eager runtime, mutable runtime, and deferred problematic globals with cycle diagnostics
 - demand-driven LLVM declarations for referenced foreign functions
 - root `main` may be parameterless or accept canonical `@std/process Init`; the generated C entry point obtains the hidden system I/O provider and constructs the init value
+- `brolang test [root]` reuses `build.bro`, discovers only explicit test-import edges, skips the
+  application entry point, and runs tests sequentially while continuing after assertion failures
 - replaceable dynamically loaded libclang C-import backend
 - C-header import caching by canonical path, target, include paths, and defines
 

README.md

@@ -73,6 +73,27 @@ linker inputs) and, like those flags, their paths are relative to the invocation
 directory. Lists take the address of an array literal; empty lists are written
 `&[]`. See `examples/build/` for runnable projects.
 
+Projects can declare tests directly and run them with `brolang test [root]`.
+The command reads the same `build.bro`, writes `build/<name>-test`, and reuses
+its C link inputs, libraries, include paths, and defines.
+
+```bro
+math :: import "../math"
+testing :: import "@std/testing"
+
+test import "../math"
+
+addition test {
+	try testing.expect(math.add(20, 22) == 42)
+	try testing.expect_equal(42, math.add(20, 22))
+}
+```
+
+`test import` discovers tests transitively without creating a namespace;
+calling package code still requires an ordinary import. Ordinary imports do
+not discover dependency tests. Assertions report their source location, a
+failure ends only the current test, and the runner continues with the suite.
+
 Relative `.h` imports create synthetic package namespaces backed by libclang:
 
 ```bro

TODO.md

@@ -897,6 +897,16 @@
   - `tag!` reads or folds a tagged union discriminant, while `tagname!` turns a comptime-known enum
     value into its immutable field-name string
 
+41. native test framework (implemented; v1)
+  - `name test { ... }` declares an implicit `void ! testing.Error` test omitted from executable builds
+  - anonymous `test import` edges discover dependency tests transitively; ordinary imports remain
+    separate namespaces and never discover tests
+  - direct `@std/testing` `expect` and expected-first `expect_equal` calls inject their source locations
+  - `brolang test` reuses `build.bro`, runs tests sequentially, continues after assertion failures,
+    prints a summary, and returns failure when a test fails or traps
+  - filtering, skipping, fixtures, snapshots, parallelism, isolation, allocators, and more assertion
+    families remain deferred
+
 ## A word on unchecked casts
 
 For casts that bypass safety checks, Honey provides builtin functions:

compiler/ast/ast.odin

@@ -227,6 +227,7 @@ Function :: struct {
 	c_abi:      bool,
 	imported:   bool,
 	generated:  bool,
+	test:       bool,
 	file_hidden: bool,
 	has_body:   bool,
 	variadic:   bool,
@@ -276,6 +277,7 @@ Import :: struct {
 	target:     Package_Id,
 	valid:      bool,
 	used:       bool,
+	test_only:  bool,
 	diagnostic: source.Diagnostic_Id,
 }
 
@@ -310,9 +312,15 @@ Package :: struct {
 	path:      string,
 	name:      symbol.Id,
 	available: bool,
+	test:      bool,
 	kind:      Package_Kind,
 }
 
+Compile_Mode :: enum u8 {
+	Executable,
+	Test,
+}
+
 Package_Kind :: enum u8 {
 	Native,
 	C_Header,

compiler/build.odin

@@ -43,26 +43,7 @@ destroy_build_config :: proc(cfg: ^BuildConfig) {
 	delete(cfg.c_options.defines)
 }
 
-// run_build implements `brolang build [root]`: it loads and type-checks
+load_build_config :: proc(project_root: string) -> (BuildConfig, bool) {
-// `root/build.bro`, reads its `config` constant, and compiles the program
-// package the config names. build.bro is only checked (never lowered/emitted),
-// so the config is read straight from the HIR.
-run_build :: proc(root: string) -> int {
-	project_root := root
-	owns_project_root := false
-	if len(project_root) == 0 {
-		found_root, found := find_build_root()
-		if !found {
-			fmt.eprintln("brolang build: could not find build.bro in the current directory or any parent")
-			return 2
-		}
-		project_root = found_root
-		owns_project_root = true
-	}
-	defer if owns_project_root {
-		delete(project_root)
-	}
-
 	sources := source.init_store()
 	defer source.destroy_store(&sources)
 	diagnostics := source.init_store_diagnostics(&sources)
@@ -73,7 +54,7 @@ run_build :: proc(root: string) -> int {
 	arena: vmem.Arena
 	if err := vmem.arena_init_growing(&arena); err != nil {
 		fmt.eprintln("failed to initialize build arena:", err)
-		return 2
+		return {}, false
 	}
 	defer vmem.arena_destroy(&arena)
 	a := vmem.arena_allocator(&arena)
@@ -82,7 +63,7 @@ run_build :: proc(root: string) -> int {
 	if !loaded {
 		source.print_all(&diagnostics)
 		fmt.eprintln("failed to load build root:", project_root)
-		return 2
+		return {}, false
 	}
 	// check needs no `main`: it synthesizes a trap main and emits one benign
 	// "missing main" diagnostic, which is expected for build.bro. Suppress that
@@ -90,10 +71,32 @@ run_build :: proc(root: string) -> int {
 	hir_module := checker.check(&ast_module, &diagnostics, &symbols, target.DEFAULT, a)
 	if build_bro_has_errors(&diagnostics) {
 		source.print_all(&diagnostics)
-		return 2
+		return {}, false
+	}
+	return extract_build_config(&hir_module, &symbols)
 }
 
-	cfg, ok := extract_build_config(&hir_module, &symbols)
+project_root_for_command :: proc(root, command: string) -> (string, bool, bool) {
+	if len(root) > 0 {
+		return root, false, true
+	}
+	project_root, found := find_build_root()
+	if !found {
+		fmt.eprintfln("brolang %s: could not find build.bro in the current directory or any parent", command)
+		return "", false, false
+	}
+	return project_root, true, true
+}
+
+// run_build implements `brolang build [root]`: it reads build.bro and compiles
+// the configured program package.
+run_build :: proc(root: string) -> int {
+	project_root, owned, found := project_root_for_command(root, "build")
+	if !found {
+		return 2
+	}
+	defer if owned {delete(project_root)}
+	cfg, ok := load_build_config(project_root)
 	if !ok {
 		return 2
 	}
@@ -109,6 +112,48 @@ run_build :: proc(root: string) -> int {
 	return compile_package(program, output, cfg.link_arguments, target.DEFAULT, cfg.c_options, project_root)
 }
 
+run_tests :: proc(root: string) -> int {
+	project_root, owned, found := project_root_for_command(root, "test")
+	if !found {
+		return 2
+	}
+	defer if owned {delete(project_root)}
+	cfg, ok := load_build_config(project_root)
+	if !ok {
+		return 2
+	}
+	defer destroy_build_config(&cfg)
+
+	program := filepath.join({project_root, cfg.source_dir})
+	defer delete(program)
+	test_name := fmt.aprintf("%s-test", cfg.output_name)
+	defer delete(test_name)
+	output, output_ok := build_output_path(project_root, test_name)
+	if !output_ok {
+		return 2
+	}
+	defer delete(output)
+	status := compile_package(
+		program, output, cfg.link_arguments, target.DEFAULT, cfg.c_options, project_root, .Test,
+	)
+	if status != 0 {
+		return status
+	}
+	state, stdout, stderr, err := os2.process_exec(
+		os2.Process_Desc{command=[]string{output}},
+		context.allocator,
+	)
+	defer delete(stdout)
+	defer delete(stderr)
+	if len(stdout) > 0 {fmt.print(string(stdout))}
+	if len(stderr) > 0 {fmt.eprint(string(stderr))}
+	if err != nil {
+		fmt.eprintln("failed to run test executable:", err)
+		return 2
+	}
+	return 0 if state.exit_code == 0 else 1
+}
+
 valid_output_name :: proc(name: string) -> bool {
 	return len(name) > 0 && name != "." && name != ".." &&
 	       !strings.contains(name, "/") && !strings.contains(name, "\\")

compiler/checker/checker.odin

@@ -1386,9 +1386,20 @@ build_symbol_indexes :: proc(checker: ^Checker) {
 	}
 	slice.sort_by(checker.global_index, global_index_less)
 
-	checker.import_index = make([]Import_Index_Entry, len(checker.ast_module.imports), checker.allocator)
+	import_count := 0
+	for import_item in checker.ast_module.imports {
+		if !import_item.test_only {
+			import_count += 1
+		}
+	}
+	checker.import_index = make([]Import_Index_Entry, import_count, checker.allocator)
+	import_index := 0
 	for import_item, id in checker.ast_module.imports {
-		checker.import_index[id] = Import_Index_Entry{scope=import_item.file, name=import_item.alias, id=ast.import_id(id)}
+		if import_item.test_only {
+			continue
+		}
+		checker.import_index[import_index] = Import_Index_Entry{scope=import_item.file, name=import_item.alias, id=ast.import_id(id)}
+		import_index += 1
 	}
 	slice.sort_by(checker.import_index, import_index_less)
 }
@@ -12874,7 +12885,7 @@ check :: proc(
 	main_template := find_template(&checker, checker.main_symbol, 0)
 	main_declarations := 0
 	for function in ast_module.functions {
-		if function.pkg == 0 && function.name == checker.main_symbol {
+		if !function.generated && function.pkg == 0 && function.name == checker.main_symbol {
 			main_declarations += 1
 		}
 	}
@@ -12917,7 +12928,7 @@ check :: proc(
 	delete(states, allocator)
 	propagate_problems(&checker)
 	for import_item in ast_module.imports {
-		if import_item.valid && !import_item.used {
+		if !import_item.test_only && import_item.valid && !import_item.used {
 			source.addf_warning(diagnostics, import_item.span, "unused import '%s'", symbol_text(&checker, import_item.alias))
 		}
 	}

compiler/compiler.odin

@@ -1,5 +1,6 @@
 package compiler
 
+import "./ast"
 import "./backend"
 import "./cimport"
 import "./checker"
@@ -34,6 +35,7 @@ compile_package :: proc(
 	selected := target.DEFAULT,
 	c_options := cimport.Options{},
 	project_root := "",
+	mode := ast.Compile_Mode.Executable,
 ) -> int {
 	sources := source.init_store()
 	defer source.destroy_store(&sources)
@@ -77,12 +79,18 @@ compile_package :: proc(
 		c_options,
 		selected,
 		project_root if len(project_root) > 0 else input_path,
+		mode,
 	)
 	if !loaded {
 		source.print_all(&diagnostics)
 		fmt.eprintln("failed to load root package directory:", input_path)
 		return 2
 	}
+	effective_root := project_root if len(project_root) > 0 else input_path
+	if !prepare_tests(&ast_module, &sources, &diagnostics, &symbols, mode, effective_root) {
+		source.print_all(&diagnostics)
+		return 1
+	}
 
 	// Generated C trampolines (for `static inline` imports) must be compiled and
 	// linked with the program. Write them out and add the source as a link input

compiler/lexer/lexer.odin

@@ -14,6 +14,7 @@ is_identifier_continue :: proc(value: byte) -> bool {
 
 keyword_kind :: proc(text: string) -> token.Kind {
 	switch text {
+	case "test":          return .Keyword_Test
 	case "func":          return .Keyword_Func
 	case "c_func":        return .Keyword_C_Func
 	case "struct":        return .Keyword_Struct

compiler/loader/loader.odin

@@ -26,6 +26,7 @@ State :: struct {
 	c_options:       cimport.Options,
 	selected:        target.Target,
 	project_root:    string,
+	mode:            ast.Compile_Mode,
 	record_identities: [dynamic]string,
 	record_types:      [dynamic]types.Type,
 	root_failed:     bool,
@@ -1130,7 +1131,42 @@ load_header :: proc(state: ^State, path: string, import_span: source.Span) -> as
 	return pkg_id
 }
 
-load_package :: proc(state: ^State, path: string, import_span: source.Span, is_root := false) -> ast.Package_Id {
+resolve_package_imports :: proc(state: ^State, pkg_id: ast.Package_Id) {
+	if int(pkg_id) >= len(state.module.packages) {
+		return
+	}
+	canonical := state.module.packages[pkg_id].path
+	import_count := len(state.module.imports)
+	for import_id in 0..<import_count {
+		import_item := state.module.imports[import_id]
+		if import_item.pkg != pkg_id || import_item.target != ast.INVALID_PACKAGE ||
+		   import_item.test_only && (state.mode != .Test || !state.module.packages[pkg_id].test) {
+			continue
+		}
+		if filepath.is_abs(import_item.path) {
+			state.module.imports[import_id].diagnostic = source.add(state.diagnostics, import_item.span, "absolute import paths are invalid")
+			state.module.imports[import_id].valid = false
+			state.module.imports[import_id].target = add_placeholder(state, import_item.path)
+			continue
+		}
+		target_path, target_ok := resolve_import_path(state, canonical, import_item.path)
+		target := load_header(state, target_path, import_item.span) if filepath.ext(import_item.path) == ".h" else
+		          load_package(state, target_path, import_item.span, include_tests=import_item.test_only)
+		state.module.imports[import_id].target = target
+		if !target_ok || target == ast.INVALID_PACKAGE || !state.module.packages[target].available {
+			state.module.imports[import_id].valid = false
+		}
+		delete(target_path, state.allocator)
+	}
+}
+
+load_package :: proc(
+	state: ^State,
+	path: string,
+	import_span: source.Span,
+	is_root := false,
+	include_tests := false,
+) -> ast.Package_Id {
 	canonical, ok := filepath.abs(path, state.allocator)
 	if !ok || !os.is_dir(path) {
 		if is_root {
@@ -1152,6 +1188,10 @@ load_package :: proc(state: ^State, path: string, import_span: source.Span, is_r
 		return id
 	}
 	if existing := find_package(state, canonical); existing != ast.INVALID_PACKAGE {
+		if include_tests && !state.module.packages[existing].test {
+			state.module.packages[existing].test = true
+			resolve_package_imports(state, existing)
+		}
 		delete(canonical, state.allocator)
 		return existing
 	}
@@ -1161,6 +1201,7 @@ load_package :: proc(state: ^State, path: string, import_span: source.Span, is_r
 		path=canonical,
 		name=symbol.intern(state.symbols, filepath.base(canonical)),
 		available=true,
+		test=state.mode == .Test && is_root || include_tests,
 	})
 	files, files_ok := read_package_files(state, canonical)
 	if !files_ok {
@@ -1204,26 +1245,7 @@ load_package :: proc(state: ^State, path: string, import_span: source.Span, is_r
 	}
 	os.file_info_slice_delete(files, state.allocator)
 
-	import_count := len(state.module.imports)
+	resolve_package_imports(state, pkg_id)
-	for import_id in 0..<import_count {
-		import_item := state.module.imports[import_id]
-		if import_item.pkg != pkg_id || import_item.target != ast.INVALID_PACKAGE {
-			continue
-		}
-		if filepath.is_abs(import_item.path) {
-			state.module.imports[import_id].diagnostic = source.add(state.diagnostics, import_item.span, "absolute import paths are invalid")
-			state.module.imports[import_id].valid = false
-			state.module.imports[import_id].target = add_placeholder(state, import_item.path)
-			continue
-		}
-		target_path, target_ok := resolve_import_path(state, canonical, import_item.path)
-		target := load_header(state, target_path, import_item.span) if filepath.ext(import_item.path) == ".h" else load_package(state, target_path, import_item.span)
-		state.module.imports[import_id].target = target
-		if !target_ok || target == ast.INVALID_PACKAGE || !state.module.packages[target].available {
-			state.module.imports[import_id].valid = false
-		}
-		delete(target_path, state.allocator)
-	}
 	return pkg_id
 }
 
@@ -1248,6 +1270,9 @@ declaration_conflicts :: proc(module: ^ast.Module, pkg: ast.Package_Id, file: as
 
 validate_imports :: proc(state: ^State) {
 	for import_item, import_id in state.module.imports {
+		if import_item.test_only {
+			continue
+		}
 		if !symbol.is_valid(import_item.alias) && import_item.target != ast.INVALID_PACKAGE {
 			state.module.imports[import_id].alias = state.module.packages[import_item.target].name
 		}
@@ -1287,7 +1312,7 @@ validate_imports :: proc(state: ^State) {
 
 find_type_import :: proc(module: ^ast.Module, file: ast.File_Id, alias: symbol.Id) -> ast.Import_Id {
 	for import_item, index in module.imports {
-		if import_item.file == file && import_item.alias == alias {
+		if !import_item.test_only && import_item.file == file && import_item.alias == alias {
 			return ast.import_id(index)
 		}
 	}
@@ -1879,6 +1904,7 @@ load :: proc(
 	c_options := cimport.Options{},
 	selected := target.DEFAULT,
 	project_root_path := "",
+	mode := ast.Compile_Mode.Executable,
 ) -> (ast.Module, bool) {
 	module := ast.init_module(allocator)
 	project_root_source := project_root_path if len(project_root_path) > 0 else root_path
@@ -1896,6 +1922,7 @@ load :: proc(
 		c_options=c_options,
 		selected=selected,
 		project_root=project_root,
+		mode=mode,
 	}
 	state.record_identities.allocator = allocator
 	state.record_types.allocator = allocator
@@ -1911,6 +1938,13 @@ load :: proc(
 	if root != ast.Package_Id(0) && root != ast.INVALID_PACKAGE {
 		state.root_failed = true
 	}
+	if mode == .Test {
+		testing_path, testing_error := filepath.join({project_root, "std", "testing"}, allocator)
+		if testing_error == nil {
+			_ = load_package(&state, testing_path, source.Span{})
+			delete(testing_path, allocator)
+		}
+	}
 	validate_imports(&state)
 	validate_declaration_aliases(&state)
 	resolve_enum_values(&state)

compiler/parser/parser.odin

@@ -3002,7 +3002,7 @@ decode_multiline_string :: proc(parser: ^Parser, tok: token.Token) -> string {
 	return fmt.aprintf("%s", strings.to_string(builder), allocator=parser.module.allocator)
 }
 
-parse_import :: proc(parser: ^Parser, alias: token.Token, start: token.Token) {
+parse_import :: proc(parser: ^Parser, alias: token.Token, start: token.Token, test_only := false) {
 	skip_newlines(parser)
 	path_token := current(parser)
 	if path_token.kind != .String {
@@ -3018,6 +3018,7 @@ parse_import :: proc(parser: ^Parser, alias: token.Token, start: token.Token) {
 			file=parser.file,
 			target=ast.INVALID_PACKAGE,
 			valid=false,
+			test_only=test_only,
 			diagnostic=source.INVALID_DIAGNOSTIC,
 		})
 		_ = finish_statement(parser)
@@ -3033,13 +3034,45 @@ parse_import :: proc(parser: ^Parser, alias: token.Token, start: token.Token) {
 		file=parser.file,
 		target=ast.INVALID_PACKAGE,
 		valid=true,
+		test_only=test_only,
 		diagnostic=source.INVALID_DIAGNOSTIC,
 	})
 	_ = finish_statement(parser)
 }
 
+parse_test :: proc(parser: ^Parser, name: token.Token) {
+	advance(parser) // consume 'test'
+	skip_newlines(parser)
+	if current(parser).kind != .Left_Brace {
+		source.add(parser.diagnostics, current(parser).span, "expected '{' after test name")
+		_ = finish_statement(parser)
+		return
+	}
+	body := parse_block(parser)
+	append(&parser.module.functions, ast.Function{
+		span=span_from(name.span, previous(parser).span),
+		name=name.symbol,
+		pkg=parser.pkg,
+		file=parser.file,
+		test=true,
+		has_body=true,
+		result=types.VOID,
+		body=body,
+		diagnostic=source.INVALID_DIAGNOSTIC,
+	})
+}
+
 parse_top_level :: proc(parser: ^Parser) {
 	hide_token, file_hidden := allow(parser, .Keyword_Hide)
+	if current(parser).kind == .Keyword_Test && peek(parser).kind == .Keyword_Import {
+		if file_hidden {
+			source.add(parser.diagnostics, hide_token.span, "test imports cannot use 'hide'")
+		}
+		start := advance(parser)
+		advance(parser) // consume 'import'
+		parse_import(parser, token.Token{}, start, test_only=true)
+		return
+	}
 	if current(parser).kind == .Keyword_Import {
 		if file_hidden {
 			source.add(parser.diagnostics, hide_token.span, "imports are already file-local and cannot use 'hide'")
@@ -3058,6 +3091,13 @@ parse_top_level :: proc(parser: ^Parser) {
 		return
 	}
 	name := advance(parser)
+	if current(parser).kind == .Keyword_Test {
+		if file_hidden {
+			source.add(parser.diagnostics, hide_token.span, "test declarations cannot use 'hide'")
+		}
+		parse_test(parser, name)
+		return
+	}
 	if current(parser).kind == .Colon_Colon {
 		saved := parser.cursor
 		advance(parser)

compiler/testing.odin

@@ -0,0 +1,281 @@
+package compiler
+
+import "./ast"
+import "./lexer"
+import "./parser"
+import "./source"
+import "./symbol"
+import "./types"
+import "core:fmt"
+import "core:path/filepath"
+import "core:slice"
+import "core:strings"
+
+Test_Entry :: struct {
+	function:     ast.Function_Id,
+	package_path: string,
+	source_path:  string,
+	offset:       source.Offset,
+}
+
+test_entry_less :: proc(a, b: Test_Entry) -> bool {
+	if a.package_path != b.package_path {
+		return a.package_path < b.package_path
+	}
+	if a.source_path != b.source_path {
+		return a.source_path < b.source_path
+	}
+	return a.offset < b.offset
+}
+
+testing_package :: proc(module: ^ast.Module, project_root: string) -> ast.Package_Id {
+	path, err := filepath.join({project_root, "std", "testing"}, module.allocator)
+	if err != nil {
+		return ast.INVALID_PACKAGE
+	}
+	defer delete(path, module.allocator)
+	canonical, ok := filepath.abs(path, module.allocator)
+	if !ok {
+		return ast.INVALID_PACKAGE
+	}
+	defer delete(canonical, module.allocator)
+	for pkg, index in module.packages {
+		if pkg.path == canonical {
+			return ast.package_id(index)
+		}
+	}
+	return ast.INVALID_PACKAGE
+}
+
+source_file_id :: proc(module: ^ast.Module, id: source.Source_Id) -> ast.File_Id {
+	for file, index in module.files {
+		if file.source == id {
+			return ast.file_id(index)
+		}
+	}
+	return ast.INVALID_FILE
+}
+
+append_ast_expr :: proc(module: ^ast.Module, expr: ast.Expr) -> ast.Expr_Id {
+	id := ast.expr_id(len(module.exprs))
+	append(&module.exprs, expr)
+	return id
+}
+
+location_expr :: proc(
+	module: ^ast.Module,
+	sources: ^source.Store,
+	symbols: ^symbol.Table,
+	span: source.Span,
+	qualifier: symbol.Id,
+) -> ast.Expr_Id {
+	line, column := 1, 1
+	path := "<unknown>"
+	if int(span.file) < len(sources.items) {
+		file := &sources.items[span.file]
+		line, column = source.line_and_column(file, span.start)
+		path = file.path
+	}
+	string_index := u64(len(module.strings))
+	append(&module.strings, strings.clone(path, module.allocator))
+	file_expr := append_ast_expr(module, ast.Expr{
+		kind=.String, span=span, integer=string_index,
+		left=ast.INVALID_EXPR, right=ast.INVALID_EXPR,
+		diagnostic=source.INVALID_DIAGNOSTIC,
+	})
+	line_expr := append_ast_expr(module, ast.Expr{
+		kind=.Integer, span=span, integer=u64(line),
+		left=ast.INVALID_EXPR, right=ast.INVALID_EXPR,
+		diagnostic=source.INVALID_DIAGNOSTIC,
+	})
+	column_expr := append_ast_expr(module, ast.Expr{
+		kind=.Integer, span=span, integer=u64(column),
+		left=ast.INVALID_EXPR, right=ast.INVALID_EXPR,
+		diagnostic=source.INVALID_DIAGNOSTIC,
+	})
+	values := []ast.Expr_Id{file_expr, line_expr, column_expr}
+	names := []string{"file", "line", "column"}
+	fields := make([]ast.Expr_Id, 3, module.allocator)
+	for index in 0..<3 {
+		fields[index] = append_ast_expr(module, ast.Expr{
+			kind=.Keyed, span=span,
+			name=symbol.intern(symbols, names[index]),
+			left=values[index], right=ast.INVALID_EXPR,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+	}
+	return append_ast_expr(module, ast.Expr{
+		kind=.Struct_Literal, span=span,
+		qualifier=qualifier,
+		name=symbol.intern(symbols, "SourceLocation"),
+		args=fields,
+		left=ast.INVALID_EXPR, right=ast.INVALID_EXPR,
+		diagnostic=source.INVALID_DIAGNOSTIC,
+	})
+}
+
+inject_assertion_locations :: proc(
+	module: ^ast.Module,
+	sources: ^source.Store,
+	symbols: ^symbol.Table,
+	testing_pkg: ast.Package_Id,
+) {
+	expect := symbol.intern(symbols, "expect")
+	expect_equal := symbol.intern(symbols, "expect_equal")
+	original_count := len(module.exprs)
+	for index in 0..<original_count {
+		expr := &module.exprs[index]
+		if expr.kind != .Call || expr.intrinsic || !symbol.is_valid(expr.qualifier) ||
+		   (expr.name != expect && expr.name != expect_equal) {
+			continue
+		}
+		file := source_file_id(module, expr.span.file)
+		matched := false
+		for import_item in module.imports {
+			if !import_item.test_only && import_item.file == file &&
+			   import_item.alias == expr.qualifier && import_item.target == testing_pkg {
+				matched = true
+				break
+			}
+		}
+		if !matched {
+			continue
+		}
+		location := location_expr(module, sources, symbols, expr.span, expr.qualifier)
+		args := make([]ast.Expr_Id, len(expr.args)+1, module.allocator)
+		copy(args, expr.args)
+		args[len(expr.args)] = location
+		delete(expr.args, module.allocator)
+		expr.args = args
+	}
+}
+
+write_brolang_string :: proc(builder: ^strings.Builder, value: string) {
+	for byte_value in transmute([]byte)value {
+		if byte_value == '\\' || byte_value == '"' {
+			strings.write_byte(builder, '\\')
+		}
+		strings.write_byte(builder, byte_value)
+	}
+}
+
+append_runner :: proc(
+	module: ^ast.Module,
+	sources: ^source.Store,
+	diagnostics: ^source.Diagnostics,
+	symbols: ^symbol.Table,
+	testing_pkg: ast.Package_Id,
+	tests: []Test_Entry,
+) {
+	builder := strings.builder_make(module.allocator)
+	defer strings.builder_destroy(&builder)
+	strings.write_string(&builder, "main func() i32 {\n\tfailed i32 = 0\n")
+	for entry, index in tests {
+		test_id := entry.function
+		test := module.functions[test_id]
+		pkg := module.packages[test.pkg]
+		alias := fmt.tprintf("__brolang_test_%d", index)
+		name := fmt.tprintf("%s.%s", filepath.base(pkg.path), symbol.resolve(symbols, test.name))
+		strings.write_string(&builder, "\tif (!__brolang_testing.run(\"")
+		write_brolang_string(&builder, name)
+		fmt.sbprintf(&builder, "\", %s.%s)) ", alias, symbol.resolve(symbols, test.name))
+		strings.write_string(&builder, "{\n\t\tfailed += 1\n\t}\n")
+	}
+	fmt.sbprintf(&builder, "\t__brolang_testing.summary(%d - failed, failed)\n", len(tests))
+	strings.write_string(&builder, "\tif (failed != 0) return 1\n\treturn 0\n}\n")
+
+	runner_text := strings.to_string(builder)
+	source_id := source.add_source(sources, "<brolang-test-runner>", runner_text)
+	file_id := ast.file_id(len(module.files))
+	append(&module.files, ast.File{source=source_id, pkg=0})
+	stream := lexer.lex(&sources.items[source_id], diagnostics, symbols, module.allocator)
+	defer delete(stream.items)
+	parser.parse_into(&stream, &sources.items[source_id], diagnostics, module, 0, file_id)
+
+	append(&module.imports, ast.Import{
+		alias=symbol.intern(symbols, "__brolang_testing"),
+		path=strings.clone("@std/testing", module.allocator),
+		pkg=0, file=file_id, target=testing_pkg,
+		valid=true, used=true,
+		diagnostic=source.INVALID_DIAGNOSTIC,
+	})
+	for entry, index in tests {
+		test_id := entry.function
+		test := module.functions[test_id]
+		append(&module.imports, ast.Import{
+			alias=symbol.intern(symbols, fmt.tprintf("__brolang_test_%d", index)),
+			path=strings.clone(module.packages[test.pkg].path, module.allocator),
+			pkg=0, file=file_id, target=test.pkg,
+			valid=true, used=true,
+			diagnostic=source.INVALID_DIAGNOSTIC,
+		})
+	}
+}
+
+prepare_tests :: proc(
+	module: ^ast.Module,
+	sources: ^source.Store,
+	diagnostics: ^source.Diagnostics,
+	symbols: ^symbol.Table,
+	mode: ast.Compile_Mode,
+	project_root: string,
+) -> bool {
+	if mode == .Executable {
+		for &function in module.functions {
+			if !function.test {
+				continue
+			}
+			function.generated = true
+			for &import_item in module.imports {
+				if !import_item.test_only && import_item.file == function.file {
+					import_item.used = true
+				}
+			}
+		}
+		return true
+	}
+
+	testing_pkg := testing_package(module, project_root)
+	if testing_pkg == ast.INVALID_PACKAGE {
+		source.add(diagnostics, source.Span{}, "test builds require @std/testing")
+		return false
+	}
+	error_type := types.find_named(
+		&module.type_store,
+		u32(testing_pkg),
+		u32(symbol.intern(symbols, "Error")),
+	)
+	if !types.is_enum(error_type, &module.type_store) {
+		source.add(diagnostics, source.Span{}, "@std/testing must declare Error as an enum")
+		return false
+	}
+
+	tests: [dynamic]Test_Entry
+	tests.allocator = module.allocator
+	defer delete(tests)
+	main_name := symbol.intern(symbols, "main")
+	for &function, index in module.functions {
+		if function.test {
+			if int(function.pkg) < len(module.packages) && module.packages[function.pkg].test {
+				function.result = types.VOID
+				function.error = error_type
+				file := module.files[function.file]
+				append(&tests, Test_Entry{
+					function=ast.function_id(index),
+					package_path=module.packages[function.pkg].path,
+					source_path=sources.items[file.source].path,
+					offset=function.span.start,
+				})
+			} else {
+				function.generated = true
+			}
+		} else if function.pkg == 0 && function.name == main_name {
+			function.generated = true
+		}
+	}
+
+	slice.sort_by(tests[:], test_entry_less)
+	inject_assertion_locations(module, sources, symbols, testing_pkg)
+	append_runner(module, sources, diagnostics, symbols, testing_pkg, tests[:])
+	return true
+}

compiler/token/token.odin

@@ -50,6 +50,7 @@ Kind :: enum u8 {
 	Right_Brace,
 	Comma,
 	Pipe,
+	Keyword_Test,
 	Keyword_Func,
 	Keyword_C_Func,
 	Keyword_Struct,
@@ -118,7 +119,7 @@ Kind :: enum u8 {
 }
 
 is_keyword :: proc(kind: Kind) -> bool {
-	return kind >= .Keyword_Func && kind <= .Keyword_C_Longdouble
+	return kind >= .Keyword_Test && kind <= .Keyword_C_Longdouble
 }
 
 Token :: struct {

compiler_tests.odin

@@ -12778,3 +12778,101 @@ main func() void {
 	testing.expect(t, types.is_slice(nested_field, &hir_module.types))
 	testing.expect_value(t, types.child_type(nested_field, &hir_module.types), types.INT)
 }
+
+@(test)
+parser_records_native_tests_and_test_imports :: proc(t: ^testing.T) {
+	text := `test import "../math"
+
+addition test {
+	return
+}
+`
+	source_file := source.Source{path="tests.bro", text=text}
+	diagnostics := source.init_diagnostics(&source_file)
+	defer source.destroy_diagnostics(&diagnostics)
+	symbols := symbol.init_table()
+	defer symbol.destroy_table(&symbols)
+	stream := lexer.lex(&source_file, &diagnostics, &symbols)
+	defer delete(stream.items)
+	module := parser.parse(&stream, &source_file, &diagnostics)
+	defer ast.destroy_module(&module)
+
+	testing.expect_value(t, len(diagnostics.items), 0)
+	testing.expect_value(t, len(module.imports), 1)
+	testing.expect(t, module.imports[0].test_only)
+	testing.expect_value(t, module.imports[0].alias, symbol.INVALID)
+	testing.expect_value(t, len(module.functions), 1)
+	testing.expect(t, module.functions[0].test)
+	testing.expect_value(t, symbol.resolve(&symbols, module.functions[0].name), "addition")
+}
+
+@(test)
+native_test_framework_discovers_reports_and_preserves_main :: proc(t: ^testing.T) {
+	directory := "/tmp/brolang-test-native-framework"
+	root := "/tmp/brolang-test-native-framework/root"
+	dependency := "/tmp/brolang-test-native-framework/dependency"
+	root_path := "/tmp/brolang-test-native-framework/root/main.bro"
+	dependency_path := "/tmp/brolang-test-native-framework/dependency/math.bro"
+	test_output := "/tmp/brolang-test-native-framework-tests"
+	app_output := "/tmp/brolang-test-native-framework-app"
+	_ = os2.remove_all(directory)
+	defer _ = os2.remove_all(directory)
+	defer _ = os.remove(test_output)
+	defer _ = os.remove(app_output)
+	testing.expect(t, os2.make_directory_all(root) == nil)
+	testing.expect(t, os2.make_directory_all(dependency) == nil)
+
+	root_text := `testing :: import "@std/testing"
+
+test import "../dependency"
+
+main func() i32 { return 77 }
+
+root_passes test {
+	try testing.expect(true)
+}
+
+root_fails test {
+	try testing.expect_equal(42, 41)
+}
+
+root_continues test {
+	try testing.expect(true)
+}
+`
+	dependency_text := `testing :: import "@std/testing"
+
+dependency_passes test {
+	try testing.expect(true)
+}
+`
+	testing.expect(t, os.write_entire_file(root_path, transmute([]byte)root_text))
+	testing.expect(t, os.write_entire_file(dependency_path, transmute([]byte)dependency_text))
+
+	app_status := compiler_core.compile_package(
+		root, app_output, nil, target.DEFAULT, cimport.Options{}, ".",
+	)
+	testing.expect_value(t, app_status, 0)
+	app_state := run_executable(app_output)
+	testing.expect_value(t, app_state.exit_code, 77)
+
+	test_status := compiler_core.compile_package(
+		root, test_output, nil, target.DEFAULT, cimport.Options{}, ".", .Test,
+	)
+	testing.expect_value(t, test_status, 0)
+	state, stdout, stderr, _ := os2.process_exec(
+		os2.Process_Desc{command=[]string{test_output}},
+		context.allocator,
+	)
+	defer delete(stdout)
+	defer delete(stderr)
+	output := string(stderr)
+	testing.expect_value(t, state.exit_code, 1)
+	testing.expect(t, strings.contains(output, "PASS root.root_passes"))
+	testing.expect(t, strings.contains(output, "FAIL root.root_fails"))
+	testing.expect(t, strings.contains(output, "expected 42, found 41"))
+	testing.expect(t, strings.contains(output, "PASS root.root_continues"))
+	testing.expect(t, strings.contains(output, "PASS dependency.dependency_passes"))
+	testing.expect(t, strings.contains(output, root_path))
+	testing.expect(t, strings.contains(output, "3 passed, 1 failed"))
+}

extension.toml

@@ -9,5 +9,5 @@ languages = ["languages/brolang"]
 
 [grammars.brolang]
 repository = "file:///Users/valdemar/Developer/Personal/Languages/brolang"
-rev = "03f5445509575fb72226e8b4bbf230d7905b7b8e"
+rev = "2e8234c6a9a12326f230ea16e901ac41a1b48c99"
 path = "tree-sitter-brolang"

languages/brolang/highlights.scm

@@ -35,6 +35,7 @@
 
 (type_declaration name: (identifier) @type)
 (function_declaration name: (identifier) @function)
+(test_declaration name: (identifier) @function)
 (parameter name: (identifier) @variable.parameter)
 
 (intrinsic_call_expression function: (identifier) @function.builtin)
@@ -53,6 +54,7 @@
 
 [
   "func"
+	"test"
   "c_func"
   "struct"
   "c_struct"

main.odin

@@ -103,6 +103,9 @@ print_usage :: proc() {
 	fmt.eprintln(
 		"       brolang build [root]   (reads root/build.bro; writes root/build/name)",
 	)
+	fmt.eprintln(
+		"       brolang test [root]    (reads root/build.bro; writes and runs root/build/name-test)",
+	)
 	fmt.eprintln(
 		"       brolang new <project-path>",
 	)
@@ -122,6 +125,10 @@ is_build_command :: proc(arg: string) -> bool {
 	return arg == "build"
 }
 
+is_test_command :: proc(arg: string) -> bool {
+	return arg == "test"
+}
+
 is_new_command :: proc(arg: string) -> bool {
 	return arg == "new"
 }
@@ -609,6 +616,14 @@ main :: proc() {
 		root := os2.args[2] if len(os2.args) == 3 else ""
 		os2.exit(compiler.run_build(root))
 	}
+	if len(os2.args) >= 2 && is_test_command(os2.args[1]) {
+		if len(os2.args) > 3 {
+			print_usage()
+			os2.exit(2)
+		}
+		root := os2.args[2] if len(os2.args) == 3 else ""
+		os2.exit(compiler.run_tests(root))
+	}
 	if len(os2.args) >= 2 && is_new_command(os2.args[1]) {
 		if len(os2.args) != 3 {
 			print_usage()

std/testing/testing.bro

@@ -0,0 +1,39 @@
+debug :: import "@std/debug"
+
+Error :: enum {
+	expectation_failed
+}
+
+SourceLocation :: struct {
+	file   []u8
+	line   usize
+	column usize
+}
+
+expect func(condition bool, location SourceLocation) void ! Error {
+	if (!condition) {
+		debug.print("{s}:{d}:{d}: expectation failed\n", {location.file, location.line, location.column})
+		return .expectation_failed
+	}
+}
+
+expect_equal func($T type, expected, actual T, location SourceLocation) void ! Error {
+	if (expected != actual) {
+		debug.print("{s}:{d}:{d}: expected {}, found {}\n", {location.file, location.line, location.column, expected, actual})
+		return .expectation_failed
+	}
+}
+
+run func(name []u8, callback *func() void ! Error) bool {
+	debug.print("RUN  {s}\n", {name,})
+	callback() catch |_| {
+		debug.print("FAIL {s}\n", {name,})
+		return false
+	}
+	debug.print("PASS {s}\n", {name,})
+	return true
+}
+
+summary func(passed, failed i32) void {
+	debug.print("{d} passed, {d} failed\n", {passed, failed})
+}

tree-sitter-brolang/grammar.js

@@ -40,7 +40,9 @@ module.exports = grammar({
 
     _top_level_declaration: $ => choice(
       $.import_declaration,
+      $.test_import_declaration,
       $.function_declaration,
+      $.test_declaration,
       $.type_declaration,
       $.global_constant_declaration,
       $.global_variable_declaration,
@@ -53,6 +55,20 @@ module.exports = grammar({
       field('path', $.string),
     ),
 
+    test_import_declaration: $ => seq(
+      'test',
+      'import',
+      repeat($._newline),
+      field('path', $.string),
+    ),
+
+    test_declaration: $ => seq(
+      field('name', $.identifier),
+      'test',
+      repeat($._newline),
+      field('body', $.block),
+    ),
+
     function_declaration: $ => seq(
       optional('hide'),
       field('name', $.identifier),

tree-sitter-brolang/queries/highlights.scm

@@ -35,6 +35,7 @@
 
 (type_declaration name: (identifier) @type)
 (function_declaration name: (identifier) @function)
+(test_declaration name: (identifier) @function)
 (parameter name: (identifier) @variable.parameter)
 
 (intrinsic_call_expression function: (identifier) @function.builtin)
@@ -53,6 +54,7 @@
 
 [
   "func"
+	"test"
   "c_func"
   "struct"
   "c_struct"

tree-sitter-brolang/src/grammar.json

@@ -26,10 +26,18 @@
           "type": "SYMBOL",
           "name": "import_declaration"
         },
+        {
+          "type": "SYMBOL",
+          "name": "test_import_declaration"
+        },
         {
           "type": "SYMBOL",
           "name": "function_declaration"
         },
+        {
+          "type": "SYMBOL",
+          "name": "test_declaration"
+        },
         {
           "type": "SYMBOL",
           "name": "type_declaration"
@@ -100,6 +108,66 @@
         }
       ]
     },
+    "test_import_declaration": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "STRING",
+          "value": "test"
+        },
+        {
+          "type": "STRING",
+          "value": "import"
+        },
+        {
+          "type": "REPEAT",
+          "content": {
+            "type": "SYMBOL",
+            "name": "_newline"
+          }
+        },
+        {
+          "type": "FIELD",
+          "name": "path",
+          "content": {
+            "type": "SYMBOL",
+            "name": "string"
+          }
+        }
+      ]
+    },
+    "test_declaration": {
+      "type": "SEQ",
+      "members": [
+        {
+          "type": "FIELD",
+          "name": "name",
+          "content": {
+            "type": "SYMBOL",
+            "name": "identifier"
+          }
+        },
+        {
+          "type": "STRING",
+          "value": "test"
+        },
+        {
+          "type": "REPEAT",
+          "content": {
+            "type": "SYMBOL",
+            "name": "_newline"
+          }
+        },
+        {
+          "type": "FIELD",
+          "name": "body",
+          "content": {
+            "type": "SYMBOL",
+            "name": "block"
+          }
+        }
+      ]
+    },
     "function_declaration": {
       "type": "SEQ",
       "members": [

tree-sitter-brolang/src/node-types.json

@@ -1852,6 +1852,14 @@
           "type": "import_declaration",
           "named": true
         },
+        {
+          "type": "test_declaration",
+          "named": true
+        },
+        {
+          "type": "test_import_declaration",
+          "named": true
+        },
         {
           "type": "type_declaration",
           "named": true
@@ -2000,6 +2008,48 @@
       ]
     }
   },
+  {
+    "type": "test_declaration",
+    "named": true,
+    "fields": {
+      "body": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "block",
+            "named": true
+          }
+        ]
+      },
+      "name": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "identifier",
+            "named": true
+          }
+        ]
+      }
+    }
+  },
+  {
+    "type": "test_import_declaration",
+    "named": true,
+    "fields": {
+      "path": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "string",
+            "named": true
+          }
+        ]
+      }
+    }
+  },
   {
     "type": "tuple_literal",
     "named": true,
@@ -2737,6 +2787,10 @@
     "type": "struct",
     "named": false
   },
+  {
+    "type": "test",
+    "named": false
+  },
   {
     "type": "true",
     "named": false

tree-sitter-brolang/test/corpus/syntax.txt

@@ -366,6 +366,29 @@ main func() void {
                 (expression
               (identifier))))))))))
 
+==================
+Native tests
+==================
+
+math :: import "../math"
+test import "../math"
+
+addition test {}
+
+---
+
+(source_file
+  (import_declaration
+    (identifier)
+    (string
+      (string_content)))
+  (test_import_declaration
+    (string
+      (string_content)))
+  (test_declaration
+    (identifier)
+    (block)))
+
 ==================
 Expanded match arms
 ==================
@@ -373,7 +396,7 @@ Expanded match arms
 Kind :: enum { one, two }
 Value :: union(enum) { number i32, empty void }
 
-test func(kind Kind, value Value) void {
+visit func(kind Kind, value Value) void {
 	match kind {
 		.one: {}
 		expand |tag|: _ = tag