diff --git a/.vscode/launch.json b/.vscode/launch.json
index 1a01f6d..055dd73 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -304,5 +304,329 @@
             "console": "integratedTerminal",
             "preLaunchTask": "build day 25",
         },
+        {
+            "name": "all tests",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_all.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests",
+        },
+        {
+            "name": "tests: util.zig",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_util.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests util",
+        },
+        {
+            "name": "tests: day 01",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day01.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day01",
+        },
+        {
+            "name": "tests: day 02",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day02.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day02",
+        },
+        {
+            "name": "tests: day 03",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day03.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day03",
+        },
+        {
+            "name": "tests: day 04",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day04.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day04",
+        },
+        {
+            "name": "tests: day 05",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day05.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day05",
+        },
+        {
+            "name": "tests: day 06",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day06.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day06",
+        },
+        {
+            "name": "tests: day 07",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day07.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day07",
+        },
+        {
+            "name": "tests: day 08",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day08.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day08",
+        },
+        {
+            "name": "tests: day 09",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day09.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day09",
+        },
+        {
+            "name": "tests: day 10",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day10.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day10",
+        },
+        {
+            "name": "tests: day 11",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day11.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day11",
+        },
+        {
+            "name": "tests: day 12",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day12.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day12",
+        },
+        {
+            "name": "tests: day 13",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day13.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day13",
+        },
+        {
+            "name": "tests: day 14",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day14.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day14",
+        },
+        {
+            "name": "tests: day 15",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day15.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day15",
+        },
+        {
+            "name": "tests: day 16",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day16.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day16",
+        },
+        {
+            "name": "tests: day 17",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day17.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day17",
+        },
+        {
+            "name": "tests: day 18",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day18.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day18",
+        },
+        {
+            "name": "tests: day 19",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day19.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day19",
+        },
+        {
+            "name": "tests: day 20",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day20.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day20",
+        },
+        {
+            "name": "tests: day 21",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day21.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day21",
+        },
+        {
+            "name": "tests: day 22",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day22.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day22",
+        },
+        {
+            "name": "tests: day 23",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day23.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day23",
+        },
+        {
+            "name": "tests: day 24",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day24.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day24",
+        },
+        {
+            "name": "tests: day 25",
+            "type": "cppvsdbg",
+            "request": "launch",
+            "program": "${workspaceFolder}/zig-out/bin/test_day25.exe",
+            "args": ["std.testing.zig_exe_path is unavailable"],
+            "stopAtEntry": false,
+            "cwd": "${workspaceFolder}",
+            "environment": [],
+            "console": "integratedTerminal",
+            "preLaunchTask": "build tests day25",
+        },
     ]
 }
\ No newline at end of file
diff --git a/.vscode/tasks.json b/.vscode/tasks.json
index b729699..b02a726 100644
--- a/.vscode/tasks.json
+++ b/.vscode/tasks.json
@@ -204,15 +204,228 @@
             "group": "build",
         },
         {
-            "label": "test",
+            "label": "build tests",
             "type": "shell",
             "command": "zig",
-            "args": ["build", "test"],
+            "args": ["build", "install_tests"],
             "problemMatcher": [],
-            "group": {
-                "kind": "test",
-                "isDefault": true
-            }
+            "group": "build",
+        },
+        {
+            "label": "build tests util",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_util"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day01",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day01"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day02",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day02"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day03",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day03"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day04",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day04"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day05",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day05"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day06",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day06"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day06",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day06"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day07",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day07"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day08",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day08"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day09",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day09"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day10",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day10"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day11",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day11"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day12",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day12"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day13",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day13"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day14",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day14"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day15",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day15"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day16",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day16"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day17",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day17"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day18",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day18"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day19",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day19"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day20",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day20"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day21",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day21"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day22",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day22"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day23",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day23"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day24",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day24"],
+            "problemMatcher": [],
+            "group": "build",
+        },
+        {
+            "label": "build tests day25",
+            "type": "shell",
+            "command": "zig",
+            "args": ["build", "install_tests_day25"],
+            "problemMatcher": [],
+            "group": "build",
         },
         {
             "label": "format",
diff --git a/build.zig b/build.zig
index 10de16e..0e8dfe0 100644
--- a/build.zig
+++ b/build.zig
@@ -5,10 +5,6 @@ const LibExeObjStep = std.build.LibExeObjStep;
 // set this to true to link libc
 const should_link_libc = false;
 
-const test_files = [_][]const u8{
-    // list any zig files with tests here
-};
-
 fn linkObject(b: *Builder, obj: *LibExeObjStep) void {
     if (should_link_libc) obj.linkLibC();
     _ = b;
@@ -16,7 +12,21 @@ fn linkObject(b: *Builder, obj: *LibExeObjStep) void {
     // Add linking for packages or third party libraries here
 }
 
+const required_zig_version = std.SemanticVersion.parse("0.9.0-dev.1920+de81c504b") catch unreachable;
+
 pub fn build(b: *Builder) void {
+    if (comptime @import("builtin").zig_version.order(required_zig_version) == .lt) {
+        std.debug.print(
+            \\Error: Your version of Zig is missing features that are needed for this template.
+            \\You will need to download a newer build.
+            \\
+            \\    https://ziglang.org/download/
+            \\
+            \\
+        , .{});
+        std.os.exit(1);
+    }
+
     // Standard target options allows the person running `zig build` to choose
     // what target to build for. Here we do not override the defaults, which
     // means any target is allowed, and the default is native. Other options
@@ -28,6 +38,7 @@ pub fn build(b: *Builder) void {
     const mode = b.standardReleaseOptions();
 
     const install_all = b.step("install_all", "Install all days");
+    const install_all_tests = b.step("install_tests_all", "Install tests for all days");
     const run_all = b.step("run_all", "Run all days");
 
     // Set up an exe for each day
@@ -45,11 +56,39 @@ pub fn build(b: *Builder) void {
 
         const install_cmd = b.addInstallArtifact(exe);
 
-        const step_key = b.fmt("install_{s}", .{dayString});
-        const step_desc = b.fmt("Install {s}.exe", .{dayString});
-        const install_step = b.step(step_key, step_desc);
-        install_step.dependOn(&install_cmd.step);
-        install_all.dependOn(&install_cmd.step);
+        const run_test = b.addTest(zigFile);
+        run_test.setTarget(target);
+        run_test.setBuildMode(mode);
+        linkObject(b, exe);
+
+        const build_test = b.addTestExe(b.fmt("test_{s}", .{dayString}), zigFile);
+        build_test.setTarget(target);
+        build_test.setBuildMode(mode);
+        linkObject(b, exe);
+        const install_test = b.addInstallArtifact(build_test);
+
+        {
+            const step_key = b.fmt("install_{s}", .{dayString});
+            const step_desc = b.fmt("Install {s}.exe", .{dayString});
+            const install_step = b.step(step_key, step_desc);
+            install_step.dependOn(&install_cmd.step);
+            install_all.dependOn(&install_cmd.step);
+        }
+
+        {
+            const step_key = b.fmt("test_{s}", .{dayString});
+            const step_desc = b.fmt("Run tests in {s}", .{zigFile});
+            const step = b.step(step_key, step_desc);
+            step.dependOn(&run_test.step);
+        }
+
+        {
+            const step_key = b.fmt("install_tests_{s}", .{dayString});
+            const step_desc = b.fmt("Install test_{s}.exe", .{dayString});
+            const step = b.step(step_key, step_desc);
+            step.dependOn(&install_test.step);
+            install_all_tests.dependOn(&install_test.step);
+        }
 
         const run_cmd = exe.run();
         run_cmd.step.dependOn(&install_cmd.step);
@@ -63,14 +102,45 @@ pub fn build(b: *Builder) void {
         run_all.dependOn(&run_cmd.step);
     }
 
-    // Set up a step to run all tests
-    const test_step = b.step("test", "Run all tests");
-    for (test_files) |file| {
-        const test_cmd = b.addTest(file);
+    // Set up tests for util.zig
+    {
+        const test_util = b.step("test_util", "Run tests in util.zig");
+        const test_cmd = b.addTest("src/util.zig");
         test_cmd.setTarget(target);
         test_cmd.setBuildMode(mode);
         linkObject(b, test_cmd);
+        test_util.dependOn(&test_cmd.step);
+    }
 
+    // Set up test executable for util.zig
+    {
+        const test_util = b.step("install_tests_util", "Run tests in util.zig");
+        const test_exe = b.addTestExe("test_util", "src/util.zig");
+        test_exe.setTarget(target);
+        test_exe.setBuildMode(mode);
+        linkObject(b, test_exe);
+        const install = b.addInstallArtifact(test_exe);
+        test_util.dependOn(&install.step);
+    }
+
+    // Set up a step to run all tests
+    {
+        const test_step = b.step("test", "Run all tests");
+        const test_cmd = b.addTest("src/test_all.zig");
+        test_cmd.setTarget(target);
+        test_cmd.setBuildMode(mode);
+        linkObject(b, test_cmd);
         test_step.dependOn(&test_cmd.step);
     }
+
+    // Set up a step to build tests (but not run them)
+    {
+        const test_build = b.step("install_tests", "Install test_all.exe");
+        const test_exe = b.addTestExe("test_all", "src/test_all.zig");
+        test_exe.setTarget(target);
+        test_exe.setBuildMode(mode);
+        linkObject(b, test_exe);
+        const test_exe_install = b.addInstallArtifact(test_exe);
+        test_build.dependOn(&test_exe_install.step);
+    }
 }
diff --git a/src/test_all.zig b/src/test_all.zig
new file mode 100644
index 0000000..75e7b6f
--- /dev/null
+++ b/src/test_all.zig
@@ -0,0 +1,29 @@
+test {
+    _ = @import("util.zig");
+    _ = @import("day01.zig");
+    _ = @import("day02.zig");
+    _ = @import("day03.zig");
+    _ = @import("day04.zig");
+    _ = @import("day05.zig");
+    _ = @import("day06.zig");
+    _ = @import("day07.zig");
+    _ = @import("day08.zig");
+    _ = @import("day09.zig");
+    _ = @import("day10.zig");
+    _ = @import("day11.zig");
+    _ = @import("day12.zig");
+    _ = @import("day13.zig");
+    _ = @import("day14.zig");
+    _ = @import("day15.zig");
+    _ = @import("day16.zig");
+    _ = @import("day17.zig");
+    _ = @import("day18.zig");
+    _ = @import("day19.zig");
+    _ = @import("day20.zig");
+    _ = @import("day21.zig");
+    _ = @import("day22.zig");
+    _ = @import("day23.zig");
+    _ = @import("day24.zig");
+    _ = @import("day25.zig");
+    // Import any other files with tests here
+}