diff --git a/lib_dev/process.js b/lib_dev/process.js
index 8f0173ad39..469c653ffc 100644
--- a/lib_dev/process.js
+++ b/lib_dev/process.js
@@ -1,7 +1,7 @@
 import * as child_process from "node:child_process";
 import * as fs from "node:fs/promises";
 import * as path from "node:path";
-import { bsc_exe, rescript_exe, rescript_legacy_exe } from "#cli/bins";
+import { bsc_exe, rescript_exe } from "#cli/bins";
 
 /**
  * @typedef {{
@@ -33,9 +33,6 @@ export const {
   rescript,
   execBuild,
   execClean,
-  rescriptLegacy,
-  execBuildLegacy,
-  execCleanLegacy,
 } = setup();
 
 /**
@@ -210,50 +207,6 @@ export function setup(cwd = process.cwd()) {
       return exec(rescript_exe, ["clean", ...args], options);
     },
 
-    /**
-     * `rescript` legacy CLI
-     *
-     * @param {(
-     *   | "build"
-     *   | "clean"
-     *   | "format"
-     *   | "dump"
-     *   | (string & {})
-     * )} command
-     * @param {string[]} [args]
-     * @param {ExecOptions} [options]
-     * @return {Promise<ExecResult>}
-     */
-    rescriptLegacy(command, args = [], options = {}) {
-      const cliPath = path.join(
-        import.meta.dirname,
-        "../cli/rescript-legacy.js",
-      );
-      return exec("node", [cliPath, command, ...args].filter(Boolean), options);
-    },
-
-    /**
-     * Execute ReScript legacy `build` command directly
-     *
-     * @param {string[]} [args]
-     * @param {ExecOptions} [options]
-     * @return {Promise<ExecResult>}
-     */
-    execBuildLegacy(args = [], options = {}) {
-      return exec(rescript_legacy_exe, ["build", ...args], options);
-    },
-
-    /**
-     * Execute ReScript legacy `clean` command directly
-     *
-     * @param {string[]} [args]
-     * @param {ExecOptions} [options]
-     * @return {Promise<ExecResult>}
-     */
-    execCleanLegacy(args = [], options = {}) {
-      return exec(rescript_legacy_exe, ["clean", ...args], options);
-    },
-
     /**
      * Execute any binary or wrapper.
      * It should support Windows as well
diff --git a/scripts/test.js b/scripts/test.js
index 1f69ab5528..c0a4537b39 100644
--- a/scripts/test.js
+++ b/scripts/test.js
@@ -122,16 +122,14 @@ if (bsbTest) {
     if (!fs.existsSync(path.join(testDir, "input.js"))) {
       console.warn(`input.js does not exist in ${testDir}`);
     } else {
-      console.log(`testing ${file}`);
-
       // note existsSync test already ensure that it is a directory
       const out = await node("input.js", [], { cwd: testDir });
-      console.log(out.stdout);
+      process.stdout.write(out.stdout);
 
       if (out.status === 0) {
-        console.log("✅ success in", file);
+        console.log(`✅ success in ${file}`);
       } else {
-        console.log(`❌ error in ${file} with stderr:\n`, out.stderr);
+        console.log(`❌ error in ${file} with stderr:\n${out.stderr}`);
         hasError = true;
       }
     }
diff --git a/tests/build_tests/build_warn_as_error/input.js b/tests/build_tests/build_warn_as_error/input.js
index bd0e9f9473..1c69b4224f 100644
--- a/tests/build_tests/build_warn_as_error/input.js
+++ b/tests/build_tests/build_warn_as_error/input.js
@@ -1,14 +1,12 @@
 import * as assert from "node:assert";
+import { stripVTControlCharacters } from "node:util";
 import { setup } from "#dev/process";
 
 const { execBuild, execClean } = setup(import.meta.dirname);
 
 const o1 = await execBuild();
 
-// biome-ignore lint/suspicious/noControlCharactersInRegex: strip ANSI color codes from output
-const stripAnsi = s => s.replace(/\x1b\[[0-9;]*m/g, "");
-
-const first_message = stripAnsi(o1.stderr)
+const first_message = stripVTControlCharacters(o1.stderr)
   .split("\n")
   .map(s => s.trim())
   .find(s => s === "Warning number 110");
@@ -20,7 +18,7 @@ if (!first_message) {
 // Second build using --warn-error +110
 const o2 = await execBuild(["--warn-error", "+110"]);
 
-const second_message = stripAnsi(o2.stderr)
+const second_message = stripVTControlCharacters(o2.stderr)
   .split("\n")
   .map(s => s.trim())
   .find(s => s === "Warning number 110 (configured as error)");
@@ -33,7 +31,7 @@ if (!second_message) {
 // The result should not be a warning as error
 const o3 = await execBuild();
 
-const third_message = stripAnsi(o3.stderr)
+const third_message = stripVTControlCharacters(o3.stderr)
   .split("\n")
   .map(s => s.trim())
   .find(s => s === "Warning number 110 (configured as error)");
diff --git a/tests/build_tests/case3/input.js b/tests/build_tests/case3/input.js
index a95d2a5faa..d2a494dc42 100644
--- a/tests/build_tests/case3/input.js
+++ b/tests/build_tests/case3/input.js
@@ -5,9 +5,10 @@ import fs from "node:fs/promises";
 import path from "node:path";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-await execBuildLegacy();
+await execClean();
+await execBuild();
 
 const o = await fs.readFile(path.join("src", "hello.res.js"), "ascii");
 assert.ok(/HelloGen\.f/.test(o));
diff --git a/tests/build_tests/cli_compile_status/input.js b/tests/build_tests/cli_compile_status/input.js
index b736a3129a..5c377e5a38 100755
--- a/tests/build_tests/cli_compile_status/input.js
+++ b/tests/build_tests/cli_compile_status/input.js
@@ -4,30 +4,30 @@ import * as assert from "node:assert";
 import { setup } from "#dev/process";
 import { normalizeNewlines } from "#dev/utils";
 
-const { rescriptLegacy } = setup(import.meta.dirname);
+const { rescript } = setup(import.meta.dirname);
 
-// Shows compile time for `rescript build` command
-let out = await rescriptLegacy("build");
+// Shows build output for `rescript build` command
+let out = await rescript("build");
+// Timing text only appears with TTY/progress output; plain output omits it.
 assert.match(
   normalizeNewlines(out.stdout),
-  />>>> Start compiling\nDependency Finished\n>>>> Finish compiling \d+ mseconds/,
+  /Parsed \d+ source files( in [0-9.]+s)?/,
 );
-
-// Shows compile time for `rescript` command
-out = await rescriptLegacy("build");
 assert.match(
   normalizeNewlines(out.stdout),
-  />>>> Start compiling\nDependency Finished\n>>>> Finish compiling \d+ mseconds/,
+  /Compiled \d+ modules( in [0-9.]+s)?/,
 );
 
-// Doesn't show compile time for `rescript build -verbose` command
-// Because we can't be sure that -verbose is a valid argument
-// And bsb won't fail with a usage message.
-// It works this way not only for -verbose, but any other arg, including -h/--help/-help
-out = await rescriptLegacy("build", ["-verbose"]);
-
+// Shows build output for `rescript` command
+out = await rescript("");
+assert.match(
+  normalizeNewlines(out.stdout),
+  /Parsed \d+ source files( in [0-9.]+s)?/,
+);
 assert.match(
   normalizeNewlines(out.stdout),
-  /Package stack: test {2}\nDependency Finished\n/,
+  /Compiled \d+ modules( in [0-9.]+s)?/,
 );
-assert.match(normalizeNewlines(out.stdout), /ninja.exe"? -C lib[\\/]bs ?\n/);
+
+out = await rescript("build", ["-v"]);
+assert.match(normalizeNewlines(out.stdout), /Created project context/);
diff --git a/tests/build_tests/cli_help/input.js b/tests/build_tests/cli_help/input.js
index 6e0068e2a8..479effb4e7 100755
--- a/tests/build_tests/cli_help/input.js
+++ b/tests/build_tests/cli_help/input.js
@@ -1,78 +1,109 @@
 // @ts-check
 
 import * as assert from "node:assert";
+import { stripVTControlCharacters } from "node:util";
 import { setup } from "#dev/process";
 import { normalizeNewlines } from "#dev/utils";
 
-const { rescriptLegacy } = setup(import.meta.dirname);
+const { rescript } = setup(import.meta.dirname);
 
 const cliHelp =
-  "Usage: rescript <options> <subcommand>\n" +
+  "ReScript - Fast, Simple, Fully Typed JavaScript from the Future\n" +
   "\n" +
-  "`rescript` is equivalent to `rescript build`\n" +
+  "Usage: rescript [OPTIONS] <COMMAND>\n" +
   "\n" +
-  "Options:\n" +
-  "  -v, -version  display version number\n" +
-  "  -h, -help     display help\n" +
+  "Commands:\n" +
+  "  build          Build the project (default command)\n" +
+  "  watch          Build, then start a watcher\n" +
+  "  clean          Clean the build artifacts\n" +
+  "  format         Format ReScript files\n" +
+  "  compiler-args  Print the compiler arguments for a ReScript source file\n" +
+  "  help           Print this message or the help of the given subcommand(s)\n" +
   "\n" +
-  "Subcommands:\n" +
-  "  build\n" +
-  "  clean\n" +
-  "  format\n" +
-  "  dump\n" +
-  "  help\n" +
+  "Options:\n" +
+  "  -v, --verbose...  Increase logging verbosity\n" +
+  "  -q, --quiet...    Decrease logging verbosity\n" +
+  "  -h, --help        Print help\n" +
+  "  -V, --version     Print version\n" +
   "\n" +
-  "Run `rescript <subcommand> -h` for subcommand help. Examples:\n" +
-  "  rescript build -h\n" +
-  "  rescript format -h\n";
+  "Notes:\n" +
+  "  - If no command is provided, the build command is run by default. See `rescript help build` for more information.\n" +
+  "  - To create a new ReScript project, or to add ReScript to an existing project, use https://github.com/rescript-lang/create-rescript-app.\n" +
+  "  - For the legacy (pre-v12) build system, run `rescript-legacy`.\n";
 
 const buildHelp =
-  "Usage: rescript build <options> -- <ninja_options>\n" +
+  "Build the project (default command)\n" +
   "\n" +
-  "`rescript build` builds the project with dependencies\n" +
+  "Usage: rescript build [OPTIONS] [FOLDER]\n" +
   "\n" +
-  "`rescript build -- -h` for Ninja options (internal usage only; unstable)\n" +
+  "Arguments:\n" +
+  "  [FOLDER]  Path to the project or subproject. This folder must contain a rescript.json file [default: .]\n" +
   "\n" +
   "Options:\n" +
-  "  -w           Watch mode\n" +
-  "  -ws          [host]:port set up host & port for WebSocket build notifications\n" +
-  "  -verbose     Set the output to be verbose\n" +
-  "  -with-deps   *deprecated* This is the default behavior now. This option will be removed in a future release\n" +
-  '  -warn-error  Warning numbers and whether to turn them into errors, e.g., "+8+32-102"\n';
+  "  -f, --filter <FILTER>            Filter source files by regex. E.g., filter out test files for compilation while doing feature work\n" +
+  "  -v, --verbose...                 Increase logging verbosity\n" +
+  "  -a, --after-build <AFTER_BUILD>  Run an additional command after build. E.g., play a sound or run a test suite when done compiling\n" +
+  "  -q, --quiet...                   Decrease logging verbosity\n" +
+  '      --warn-error <WARN_ERROR>    Override warning configuration from rescript.json. Example: --warn-error "+3+8+11+12+26+27+31+32+33+34+35+39+44+45+110"\n' +
+  "  -n, --no-timing [<NO_TIMING>]    Disable output timing [default: false] [possible values: true, false]\n" +
+  "  -h, --help                       Print help\n";
 
 const cleanHelp =
-  "Usage: rescript clean <options>\n" +
+  "Clean the build artifacts\n" +
+  "\n" +
+  "Usage: rescript clean [OPTIONS] [FOLDER]\n" +
   "\n" +
-  "`rescript clean` cleans build artifacts\n" +
+  "Arguments:\n" +
+  "  [FOLDER]  Path to the project or subproject. This folder must contain a rescript.json file [default: .]\n" +
   "\n" +
   "Options:\n" +
-  "  -verbose    Set the output to be verbose\n" +
-  "  -with-deps  *deprecated* This is the default behavior now. This option will be removed in a future release\n";
+  "  -v, --verbose...  Increase logging verbosity\n" +
+  "  -q, --quiet...    Decrease logging verbosity\n" +
+  "  -h, --help        Print help\n";
 
 const formatHelp =
-  "Usage: rescript format <options> [files]\n" +
+  "Format ReScript files\n" +
   "\n" +
-  "`rescript format` formats the current directory\n" +
+  "Usage: rescript format [OPTIONS] [FILES]...\n" +
+  "\n" +
+  "Arguments:\n" +
+  "  [FILES]...  Files to format. If no files are provided, all files are formatted\n" +
   "\n" +
   "Options:\n" +
-  "  -stdin  [.res|.resi] Read the code from stdin and print\n" +
-  "          the formatted code to stdout in ReScript syntax\n" +
-  "  -all    Format the whole project \n" +
-  "  -check  Check formatting for file or the whole project. Use `-all` to check the whole project\n";
-
-const dumpHelp =
-  "Usage: rescript dump <options> [target]\n" +
-  "`rescript dump` dumps the information for the target\n";
+  "  -c, --check          Check formatting status without applying changes\n" +
+  "  -v, --verbose...     Increase logging verbosity\n" +
+  "  -q, --quiet...       Decrease logging verbosity\n" +
+  "  -s, --stdin <STDIN>  Read the code from stdin and print the formatted code to stdout [possible values: .res, .resi]\n" +
+  "  -h, --help           Print help\n";
+
+const compilerArgsHelp =
+  "Print the compiler arguments for a ReScript source file\n" +
+  "\n" +
+  "Usage: rescript compiler-args [OPTIONS] <PATH>\n" +
+  "\n" +
+  "Arguments:\n" +
+  "  <PATH>  Path to a ReScript source file (.res or .resi)\n" +
+  "\n" +
+  "Options:\n" +
+  "  -v, --verbose...  Increase logging verbosity\n" +
+  "  -q, --quiet...    Decrease logging verbosity\n" +
+  "  -h, --help        Print help\n";
 
 /**
  * @param {string[]} params
  * @param {{ stdout: string; stderr: string; status: number; }} expected
  */
 async function test(params, expected) {
-  const out = await rescriptLegacy("", params);
-
-  assert.equal(normalizeNewlines(out.stdout), expected.stdout);
-  assert.equal(normalizeNewlines(out.stderr), expected.stderr);
+  const out = await rescript("", params);
+
+  assert.equal(
+    normalizeNewlines(stripVTControlCharacters(out.stdout)),
+    expected.stdout,
+  );
+  assert.equal(
+    normalizeNewlines(stripVTControlCharacters(out.stderr)),
+    expected.stderr,
+  );
   assert.equal(out.status, expected.status);
 }
 
@@ -98,9 +129,16 @@ await test(["--help", "-w"], { stdout: cliHelp, stderr: "", status: 0 });
 await test(["build", "-h"], { stdout: buildHelp, stderr: "", status: 0 });
 
 // Exits with build help with unknown arg
-await test(["build", "-foo"], {
+await test(["build", "--foo"], {
   stdout: "",
-  stderr: `Error: Unknown option "-foo".\n${buildHelp}`,
+  stderr:
+    "error: unexpected argument '--foo' found\n" +
+    "\n" +
+    "  tip: to pass '--foo' as a value, use '-- --foo'\n" +
+    "\n" +
+    "Usage: rescript build [OPTIONS] [FOLDER]\n" +
+    "\n" +
+    "For more information, try '--help'.\n",
   status: 2,
 });
 
@@ -114,16 +152,17 @@ await test(["-h"], { stdout: cliHelp, stderr: "", status: 0 });
 await test(["help"], { stdout: cliHelp, stderr: "", status: 0 });
 
 // Exits with cli help with unknown command
-await test(["built"], {
-  stdout: "",
-  stderr: `Error: Unknown command "built".\n${cliHelp}`,
-  status: 2,
-});
-
-// Exits with build help with unknown args
-await test(["-foo"], {
+// Exits with build usage on unknown args
+await test(["--foo"], {
   stdout: "",
-  stderr: `Error: Unknown option "-foo".\n${buildHelp}`,
+  stderr:
+    "error: unexpected argument '--foo' found\n" +
+    "\n" +
+    "  tip: to pass '--foo' as a value, use '-- --foo'\n" +
+    "\n" +
+    "Usage: rescript build [OPTIONS] [FOLDER]\n" +
+    "\n" +
+    "For more information, try '--help'.\n",
   status: 2,
 });
 
@@ -138,9 +177,16 @@ await test(["clean", "--help"], {
 await test(["clean", "-h"], { stdout: cleanHelp, stderr: "", status: 0 });
 
 // Exits with clean help with unknown arg
-await test(["clean", "-foo"], {
+await test(["clean", "--foo"], {
   stdout: "",
-  stderr: `Error: Unknown option "-foo".\n${cleanHelp}`,
+  stderr:
+    "error: unexpected argument '--foo' found\n" +
+    "\n" +
+    "  tip: to pass '--foo' as a value, use '-- --foo'\n" +
+    "\n" +
+    "Usage: rescript clean [OPTIONS] [FOLDER]\n" +
+    "\n" +
+    "For more information, try '--help'.\n",
   status: 2,
 });
 
@@ -158,12 +204,16 @@ await test(["format", "-h"], {
   status: 0,
 });
 
-// Shows dump help with --help arg
-await test(["dump", "--help"], {
-  stdout: dumpHelp,
+// Shows compiler-args help with --help arg
+await test(["compiler-args", "--help"], {
+  stdout: compilerArgsHelp,
   stderr: "",
   status: 0,
 });
 
-// Shows dump help with -h arg
-await test(["dump", "-h"], { stdout: dumpHelp, stderr: "", status: 0 });
+// Shows compiler-args help with -h arg
+await test(["compiler-args", "-h"], {
+  stdout: compilerArgsHelp,
+  stderr: "",
+  status: 0,
+});
diff --git a/tests/build_tests/custom_namespace/input.js b/tests/build_tests/custom_namespace/input.js
index 35a776cda4..718d172356 100644
--- a/tests/build_tests/custom_namespace/input.js
+++ b/tests/build_tests/custom_namespace/input.js
@@ -1,10 +1,10 @@
 import * as assert from "node:assert";
 import { setup } from "#dev/process";
 
-const { execCleanLegacy, execBuildLegacy } = setup(import.meta.dirname);
+const { execClean, execBuild } = setup(import.meta.dirname);
 
-await execCleanLegacy();
-await execBuildLegacy();
+await execClean();
+await execBuild();
 
 const x = await import("./src/demo.res.js");
 assert.equal(x.v, 42);
diff --git a/tests/build_tests/cycle/input.js b/tests/build_tests/cycle/input.js
index 52d30d646b..acb3b692c8 100644
--- a/tests/build_tests/cycle/input.js
+++ b/tests/build_tests/cycle/input.js
@@ -1,16 +1,14 @@
 // @ts-check
 
 import * as assert from "node:assert";
-import * as fs from "node:fs/promises";
-import * as path from "node:path";
+import { stripVTControlCharacters } from "node:util";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-const output = await execBuildLegacy();
+const output = await execBuild();
+const stderr = stripVTControlCharacters(output.stderr);
 
-assert.match(output.stdout, /dependency cycle/);
-
-const compilerLogFile = path.join("lib", "bs", ".compiler.log");
-const compilerLog = await fs.readFile(compilerLogFile, "utf8");
-assert.match(compilerLog, /dependency cycle/);
+assert.match(stderr, /circular dependency/);
+assert.match(stderr, /B \(src[\\/]b\.res\)/);
+await execClean();
diff --git a/tests/build_tests/cycle1/input.js b/tests/build_tests/cycle1/input.js
index 91e21111aa..8423853bc0 100644
--- a/tests/build_tests/cycle1/input.js
+++ b/tests/build_tests/cycle1/input.js
@@ -1,17 +1,14 @@
 // @ts-check
 
 import * as assert from "node:assert";
-import * as fs from "node:fs/promises";
-import * as path from "node:path";
+import { stripVTControlCharacters } from "node:util";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy, execCleanLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-await execCleanLegacy();
-const output = await execBuildLegacy();
+await execClean();
+const output = await execBuild();
+const stderr = stripVTControlCharacters(output.stderr);
 
-assert.match(output.stdout, /is dangling/);
-
-const compilerLogFile = path.join("lib", "bs", ".compiler.log");
-const compilerLog = await fs.readFile(compilerLogFile, "utf8");
-assert.match(compilerLog, /is dangling/);
+assert.match(stderr, /dangling/i);
+await execClean();
diff --git a/tests/build_tests/devonly/input.js b/tests/build_tests/devonly/input.js
index 8300ab09a5..50a4ceabd1 100644
--- a/tests/build_tests/devonly/input.js
+++ b/tests/build_tests/devonly/input.js
@@ -2,6 +2,6 @@
 
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild } = setup(import.meta.dirname);
 
-await execBuildLegacy();
+await execBuild();
diff --git a/tests/build_tests/exports/input.js b/tests/build_tests/exports/input.js
index 50a4ceabd1..dd8449f36b 100644
--- a/tests/build_tests/exports/input.js
+++ b/tests/build_tests/exports/input.js
@@ -2,6 +2,7 @@
 
 import { setup } from "#dev/process";
 
-const { execBuild } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
 await execBuild();
+await execClean();
diff --git a/tests/build_tests/gpr_978/input.js b/tests/build_tests/gpr_978/input.js
index da8924057d..59db5484d0 100644
--- a/tests/build_tests/gpr_978/input.js
+++ b/tests/build_tests/gpr_978/input.js
@@ -1,15 +1,12 @@
 // @ts-check
 
 import * as assert from "node:assert";
-import * as fs from "node:fs/promises";
-import * as path from "node:path";
+import { stripVTControlCharacters } from "node:util";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-const output = await execBuildLegacy();
-assert.match(output.stdout, /M is exported twice/);
-
-const compilerLogFile = path.join("lib", "bs", ".compiler.log");
-const compilerLog = await fs.readFile(compilerLogFile, "utf8");
-assert.match(compilerLog, /M is exported twice/);
+const output = await execBuild();
+const stderr = stripVTControlCharacters(output.stderr);
+assert.match(stderr, /M is exported twice/);
+await execClean();
diff --git a/tests/build_tests/hyphen2/input.js b/tests/build_tests/hyphen2/input.js
index 8300ab09a5..dd8449f36b 100644
--- a/tests/build_tests/hyphen2/input.js
+++ b/tests/build_tests/hyphen2/input.js
@@ -2,6 +2,7 @@
 
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-await execBuildLegacy();
+await execBuild();
+await execClean();
diff --git a/tests/build_tests/in_source/input.js b/tests/build_tests/in_source/input.js
deleted file mode 100644
index 7b5a81ea09..0000000000
--- a/tests/build_tests/in_source/input.js
+++ /dev/null
@@ -1,9 +0,0 @@
-// @ts-check
-
-import * as assert from "node:assert";
-import { setup } from "#dev/process";
-
-const { execBuildLegacy } = setup(import.meta.dirname);
-
-const output = await execBuildLegacy(["-regen"]);
-assert.match(output.stderr, /detected two module formats/);
diff --git a/tests/build_tests/in_source/input.sh b/tests/build_tests/in_source/input.sh
deleted file mode 100644
index a8e88ce227..0000000000
--- a/tests/build_tests/in_source/input.sh
+++ /dev/null
@@ -1 +0,0 @@
-rescript build -regen
\ No newline at end of file
diff --git a/tests/build_tests/in_source/rescript.json b/tests/build_tests/in_source/rescript.json
deleted file mode 100644
index fc69fdc991..0000000000
--- a/tests/build_tests/in_source/rescript.json
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  "name": "x",
-  "sources": ".",
-  "package-specs": [
-    {
-      "module": "commonjs",
-      "in-source": true
-    },
-    {
-      "module": "esmodule",
-      "in-source": true
-    }
-  ]
-}
diff --git a/tests/build_tests/install/input.js b/tests/build_tests/install/input.js
deleted file mode 100644
index 3cb39bb44e..0000000000
--- a/tests/build_tests/install/input.js
+++ /dev/null
@@ -1,20 +0,0 @@
-// @ts-check
-
-import * as assert from "node:assert";
-import { existsSync } from "node:fs";
-import * as path from "node:path";
-import { setup } from "#dev/process";
-
-const { execBuildLegacy, execCleanLegacy } = setup(import.meta.dirname);
-
-await execCleanLegacy();
-await execBuildLegacy(["-install"]);
-
-let fooExists = existsSync(path.join("lib", "ocaml", "Foo.cmi"));
-assert.ok(!fooExists);
-
-await execBuildLegacy();
-await execBuildLegacy(["-install"]);
-
-fooExists = existsSync(path.join("lib", "ocaml", "Foo.cmi"));
-assert.ok(fooExists);
diff --git a/tests/build_tests/install/rescript.json b/tests/build_tests/install/rescript.json
deleted file mode 100644
index 331cb861e3..0000000000
--- a/tests/build_tests/install/rescript.json
+++ /dev/null
@@ -1,14 +0,0 @@
-{
-  "name": "install",
-  "sources": {
-    "dir": "src",
-    "subdirs": true
-  },
-  "package-specs": {
-    "module": "esmodule",
-    "in-source": true,
-    "suffix": ".res.js"
-  },
-  "dependencies": [],
-  "warnings": { "error": "+101" }
-}
diff --git a/tests/build_tests/install/src/Foo.res b/tests/build_tests/install/src/Foo.res
deleted file mode 100644
index 95d72e3b10..0000000000
--- a/tests/build_tests/install/src/Foo.res
+++ /dev/null
@@ -1 +0,0 @@
-let main = () => Js.log("hello")
diff --git a/tests/build_tests/install/src/Foo.res.js b/tests/build_tests/install/src/Foo.res.js
deleted file mode 100644
index 6078c7d3cf..0000000000
--- a/tests/build_tests/install/src/Foo.res.js
+++ /dev/null
@@ -1,11 +0,0 @@
-// Generated by ReScript, PLEASE EDIT WITH CARE
-
-
-function main() {
-  console.log("hello");
-}
-
-export {
-  main,
-}
-/* No side effect */
diff --git a/tests/build_tests/jsx_settings_inheritance/input.js b/tests/build_tests/jsx_settings_inheritance/input.js
index 03decbf153..6d8beddd22 100644
--- a/tests/build_tests/jsx_settings_inheritance/input.js
+++ b/tests/build_tests/jsx_settings_inheritance/input.js
@@ -2,7 +2,7 @@
 
 import { setup } from "#dev/process";
 
-const { execBuildLegacy, execCleanLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-await execCleanLegacy();
-await execBuildLegacy();
+await execClean();
+await execBuild();
diff --git a/tests/build_tests/nested/input.js b/tests/build_tests/nested/input.js
index ccd0bce50d..16b721cac2 100644
--- a/tests/build_tests/nested/input.js
+++ b/tests/build_tests/nested/input.js
@@ -5,11 +5,14 @@ import * as fs from "node:fs/promises";
 import * as path from "node:path";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-await execBuildLegacy();
+await execBuild();
 
-const content = await fs.readFile(path.join("src", "demo.js"), "utf8");
+const content = await fs.readFile(
+  path.join(import.meta.dirname, "src", "demo.js"),
+  "utf8",
+);
 
 assert.equal(content.match(/A00_a1_main/g)?.length, 3);
 assert.equal(content.match(/B00_b1_main/g)?.length, 3);
@@ -20,3 +23,4 @@ assert.equal(content.match(/b0_main/g)?.length, 1);
 
 const mod = await import("./src/demo.js");
 assert.equal(mod.v, 4, "nested");
+await execClean();
diff --git a/tests/build_tests/nnest/input.js b/tests/build_tests/nnest/input.js
index 3d346a4475..bef91995b4 100644
--- a/tests/build_tests/nnest/input.js
+++ b/tests/build_tests/nnest/input.js
@@ -5,11 +5,14 @@ import * as fs from "node:fs/promises";
 import * as path from "node:path";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-await execBuildLegacy();
+await execBuild();
 
-const content = await fs.readFile(path.join("src", "demo.js"), "utf8");
+const content = await fs.readFile(
+  path.join(import.meta.dirname, "src", "demo.js"),
+  "utf8",
+);
 
 assert.equal(content.match(/A0_a1_main/g)?.length, 3);
 assert.equal(content.match(/B0_b1_main/g)?.length, 3);
@@ -20,3 +23,4 @@ assert.equal(content.match(/b0_main/g)?.length, 1);
 
 const mod = await import("./src/demo.js");
 assert.equal(mod.v, 4, "nested");
+await execClean();
diff --git a/tests/build_tests/not_undefined_attribute/input.res b/tests/build_tests/not_undefined_attribute/demo.res
similarity index 100%
rename from tests/build_tests/not_undefined_attribute/input.res
rename to tests/build_tests/not_undefined_attribute/demo.res
diff --git a/tests/build_tests/not_undefined_attribute/input.js b/tests/build_tests/not_undefined_attribute/input.js
index 98455836ac..b37a4d14e2 100644
--- a/tests/build_tests/not_undefined_attribute/input.js
+++ b/tests/build_tests/not_undefined_attribute/input.js
@@ -1,23 +1,16 @@
 // @ts-check
 
 import * as assert from "node:assert";
+import { stripVTControlCharacters } from "node:util";
 import { setup } from "#dev/process";
 import { normalizeNewlines } from "#dev/utils";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-const out = await execBuildLegacy();
+const out = await execBuild();
+const stderr = normalizeNewlines(stripVTControlCharacters(out.stderr));
 
-assert.equal(
-  normalizeNewlines(out.stdout.slice(out.stdout.indexOf("input.res:2:1-12"))),
-  `input.res:2:1-12
-
-  1 │ @notUndefined
-  2 │ type t = int
-  3 │ 
-
-  @notUndefined can only be used on abstract types
-
-FAILED: cannot make progress due to previous errors.
-`,
-);
+assert.ok(stderr.includes("demo.res:2:1-12"));
+assert.ok(stderr.includes("@notUndefined can only be used on abstract types"));
+assert.ok(stderr.includes("Failed to Compile"));
+await execClean();
diff --git a/tests/build_tests/ns/input.js b/tests/build_tests/ns/input.js
index 8300ab09a5..50a4ceabd1 100755
--- a/tests/build_tests/ns/input.js
+++ b/tests/build_tests/ns/input.js
@@ -2,6 +2,6 @@
 
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild } = setup(import.meta.dirname);
 
-await execBuildLegacy();
+await execBuild();
diff --git a/tests/build_tests/post-build/input.js b/tests/build_tests/post-build/input.js
index 83fd43098f..97c5c5c5ea 100644
--- a/tests/build_tests/post-build/input.js
+++ b/tests/build_tests/post-build/input.js
@@ -3,7 +3,7 @@
 import * as assert from "node:assert";
 import { setup } from "#dev/process";
 
-const { execBuild } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
 if (process.platform === "win32") {
   console.log("Skipping test on Windows");
@@ -15,3 +15,5 @@ const out = await execBuild();
 if (out.status !== 0) {
   assert.fail(out.stdout + out.stderr);
 }
+
+await execClean();
diff --git a/tests/build_tests/react_ppx/input.js b/tests/build_tests/react_ppx/input.js
index 8300ab09a5..50a4ceabd1 100644
--- a/tests/build_tests/react_ppx/input.js
+++ b/tests/build_tests/react_ppx/input.js
@@ -2,6 +2,6 @@
 
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild } = setup(import.meta.dirname);
 
-await execBuildLegacy();
+await execBuild();
diff --git a/tests/build_tests/rerror/input.js b/tests/build_tests/rerror/input.js
index ddcbd1ad7d..44a9f982e0 100644
--- a/tests/build_tests/rerror/input.js
+++ b/tests/build_tests/rerror/input.js
@@ -1,17 +1,19 @@
 // @ts-check
 
 import * as assert from "node:assert";
+import { stripVTControlCharacters } from "node:util";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy, execCleanLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-await execCleanLegacy();
-const output = await execBuildLegacy([]);
+await execClean();
+const output = await execBuild();
+const stderr = stripVTControlCharacters(output.stderr);
 
 // verify the output is in reason syntax
-const u = output.stdout.match(/=>/g);
+const u = stderr.match(/=>/g);
 
-const lines = output.stdout
+const lines = stderr
   .split(/\r?\n/)
   .map(x => x.trim())
   .filter(Boolean);
@@ -19,10 +21,10 @@ const lines = output.stdout
 let test = false;
 for (let i = 0; i < lines.length; i++) {
   if (lines[i] === "We've found a bug for you!") {
-    console.log(`line ${i} found`);
     assert.match(lines[i + 1], /src[\\/]demo.res:1:21-23/);
     test = true;
   }
 }
 assert.ok(test);
 assert.equal(u?.length, 2);
+await execClean();
diff --git a/tests/build_tests/scoped_ppx/.gitignore b/tests/build_tests/scoped_ppx/.gitignore
deleted file mode 100644
index 1e5a96ef36..0000000000
--- a/tests/build_tests/scoped_ppx/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-.merlin
-!node_modules
\ No newline at end of file
diff --git a/tests/build_tests/scoped_ppx/input.js b/tests/build_tests/scoped_ppx/input.js
deleted file mode 100644
index ff1426845f..0000000000
--- a/tests/build_tests/scoped_ppx/input.js
+++ /dev/null
@@ -1,19 +0,0 @@
-// @ts-check
-
-import * as assert from "node:assert";
-import { setup } from "#dev/process";
-
-const { execBuildLegacy } = setup(import.meta.dirname);
-
-if (process.platform === "win32") {
-  console.log("Skipping test on Windows");
-  process.exit(0);
-}
-
-await execBuildLegacy();
-const output = await execBuildLegacy(["--", "-t", "commands", "src/hello.ast"]);
-
-assert.match(
-  output.stdout,
-  /-ppx '.*\/test\.js -hello' -ppx '.*\/test\.js -heyy' -ppx .*test\.js/,
-);
diff --git a/tests/build_tests/scoped_ppx/node_modules/@hongbo/ppx1/package.json b/tests/build_tests/scoped_ppx/node_modules/@hongbo/ppx1/package.json
deleted file mode 100644
index 5bbefffbab..0000000000
--- a/tests/build_tests/scoped_ppx/node_modules/@hongbo/ppx1/package.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "type": "commonjs"
-}
diff --git a/tests/build_tests/scoped_ppx/node_modules/@hongbo/ppx1/test.js b/tests/build_tests/scoped_ppx/node_modules/@hongbo/ppx1/test.js
deleted file mode 100755
index e0ec31c3e2..0000000000
--- a/tests/build_tests/scoped_ppx/node_modules/@hongbo/ppx1/test.js
+++ /dev/null
@@ -1,11 +0,0 @@
-#!/usr/bin/env node
-
-// @ts-check
-
-const fs = require('node:fs')
-
-const file_in = process.argv[process.argv.length - 2]
-const file_out = process.argv[process.argv.length - 1]
-
-fs.createReadStream(file_in)
-  .pipe(fs.createWriteStream(file_out))
diff --git a/tests/build_tests/scoped_ppx/rescript.json b/tests/build_tests/scoped_ppx/rescript.json
deleted file mode 100644
index 42483ad370..0000000000
--- a/tests/build_tests/scoped_ppx/rescript.json
+++ /dev/null
@@ -1,11 +0,0 @@
-{
-  "ppx-flags": [
-    ["@hongbo/ppx1/test.js", "-hello"],
-    ["@hongbo/ppx1/test.js", "-heyy"],
-    "@hongbo/ppx1/test.js"
-  ],
-  "sources": {
-    "dir": "src"
-  },
-  "name": "hello"
-}
diff --git a/tests/build_tests/scoped_ppx/src/hello.res b/tests/build_tests/scoped_ppx/src/hello.res
deleted file mode 100644
index ab49c6303b..0000000000
--- a/tests/build_tests/scoped_ppx/src/hello.res
+++ /dev/null
@@ -1 +0,0 @@
-let v = 1
diff --git a/tests/build_tests/transitive_dependency/input.js b/tests/build_tests/transitive_dependency/input.js
index d13102583a..765a1f4c7a 100644
--- a/tests/build_tests/transitive_dependency/input.js
+++ b/tests/build_tests/transitive_dependency/input.js
@@ -2,14 +2,25 @@
 
 import * as assert from "node:assert";
 import { existsSync } from "node:fs";
+import * as path from "node:path";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy, execCleanLegacy } = setup("./a");
-await execCleanLegacy();
-const output = await execBuildLegacy();
-console.log(output);
+const { execBuild, execClean } = setup(path.join(import.meta.dirname, "a"));
+await execClean();
+await execBuild();
 
 assert.ok(
-  !existsSync("./node_modules/c/lib/es6/tests/test.res.js"),
+  !existsSync(
+    path.join(
+      import.meta.dirname,
+      "a",
+      "node_modules",
+      "c",
+      "lib",
+      "es6",
+      "tests",
+      "test.res.js",
+    ),
+  ),
   "dev files of module 'c' were built by 'a' even though 'c' is not a dependency of 'a'",
 );
diff --git a/tests/build_tests/unboxed_bool_with_const/input.js b/tests/build_tests/unboxed_bool_with_const/input.js
index 337065eed9..623e0ab097 100644
--- a/tests/build_tests/unboxed_bool_with_const/input.js
+++ b/tests/build_tests/unboxed_bool_with_const/input.js
@@ -1,25 +1,20 @@
 // @ts-check
 
 import * as assert from "node:assert";
+import { stripVTControlCharacters } from "node:util";
 import { setup } from "#dev/process";
 import { normalizeNewlines } from "#dev/utils";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-const out = await execBuildLegacy();
+const out = await execBuild();
+const stderr = normalizeNewlines(stripVTControlCharacters(out.stderr));
 
-assert.equal(
-  normalizeNewlines(out.stdout.slice(out.stdout.indexOf("Main.res:3:3-14"))),
-  `Main.res:3:3-14
-
-  1 │ @unboxed
-  2 │ type t<'a> =
-  3 │   | Bool(bool)
-  4 │   | @as(false) False
-  5 │   | @as(true) True
-
-  This untagged variant definition is invalid: At most one case can be a boolean type.
-
-FAILED: cannot make progress due to previous errors.
-`,
+assert.ok(stderr.includes("Main.res:3:3-14"));
+assert.ok(
+  stderr.includes(
+    "This untagged variant definition is invalid: At most one case can be a boolean type.",
+  ),
 );
+assert.ok(stderr.includes("Failed to Compile"));
+await execClean();
diff --git a/tests/build_tests/uncurried-always/input.js b/tests/build_tests/uncurried-always/input.js
index 03decbf153..dd8449f36b 100644
--- a/tests/build_tests/uncurried-always/input.js
+++ b/tests/build_tests/uncurried-always/input.js
@@ -2,7 +2,7 @@
 
 import { setup } from "#dev/process";
 
-const { execBuildLegacy, execCleanLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-await execCleanLegacy();
-await execBuildLegacy();
+await execBuild();
+await execClean();
diff --git a/tests/build_tests/unicode/input.js b/tests/build_tests/unicode/input.js
index 44f701627d..c6cdc701f8 100644
--- a/tests/build_tests/unicode/input.js
+++ b/tests/build_tests/unicode/input.js
@@ -1,21 +1,19 @@
 // @ts-check
 
-import * as assert from "node:assert";
 import * as fs from "node:fs/promises";
 import * as path from "node:path";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
 if (process.platform === "win32") {
   console.log("Skipping test on Windows");
   process.exit(0);
 }
 
-await execBuildLegacy();
-const content = await fs.readFile(
-  path.join("lib", "bs", ".sourcedirs.json"),
-  "utf-8",
-);
+await execBuild();
 
-assert.ok(JSON.parse(content).dirs.some(x => x.includes("📕annotation")));
+await fs.access(
+  path.join(import.meta.dirname, "lib", "bs", "src", "📕annotation", "a.js"),
+);
+await execClean();
diff --git a/tests/build_tests/unicode/rescript.json b/tests/build_tests/unicode/rescript.json
index a8065db935..b5bd5c237a 100644
--- a/tests/build_tests/unicode/rescript.json
+++ b/tests/build_tests/unicode/rescript.json
@@ -1,7 +1,7 @@
 {
   "name": "unicode",
   "sources": {
-    "dir": ".",
+    "dir": "src",
     "subdirs": true
   }
 }
diff --git "a/tests/build_tests/unicode/\360\237\223\225annotation/a.res" "b/tests/build_tests/unicode/src/\360\237\223\225annotation/a.res"
similarity index 100%
rename from "tests/build_tests/unicode/\360\237\223\225annotation/a.res"
rename to "tests/build_tests/unicode/src/\360\237\223\225annotation/a.res"
diff --git "a/tests/build_tests/unicode/\360\237\223\227block/b.res" "b/tests/build_tests/unicode/src/\360\237\223\227block/b.res"
similarity index 100%
rename from "tests/build_tests/unicode/\360\237\223\227block/b.res"
rename to "tests/build_tests/unicode/src/\360\237\223\227block/b.res"
diff --git "a/tests/build_tests/unicode/\360\237\223\231inline/c.res" "b/tests/build_tests/unicode/src/\360\237\223\231inline/c.res"
similarity index 100%
rename from "tests/build_tests/unicode/\360\237\223\231inline/c.res"
rename to "tests/build_tests/unicode/src/\360\237\223\231inline/c.res"
diff --git a/tests/build_tests/warn_legacy_config/input.js b/tests/build_tests/warn_legacy_config/input.js
index caa8c1e192..ab47cb886f 100644
--- a/tests/build_tests/warn_legacy_config/input.js
+++ b/tests/build_tests/warn_legacy_config/input.js
@@ -3,10 +3,9 @@
 import * as assert from "node:assert";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-const output = await execBuildLegacy();
-assert.match(
-  output.stdout,
-  /^Warning: bsconfig.json is deprecated. Migrate it to rescript.json/,
-);
+const output = await execBuild();
+assert.notEqual(output.status, 0);
+assert.match(output.stderr, /no package\.json or rescript\.json file/i);
+await execClean();
diff --git a/tests/build_tests/weird_deps/input.js b/tests/build_tests/weird_deps/input.js
index 6e6f7a4cc5..1675283d2e 100644
--- a/tests/build_tests/weird_deps/input.js
+++ b/tests/build_tests/weird_deps/input.js
@@ -2,21 +2,10 @@
 
 import * as assert from "node:assert";
 import { setup } from "#dev/process";
-import { normalizeNewlines } from "#dev/utils";
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-const { execBuildLegacy } = setup(import.meta.dirname);
-
-const out = await execBuildLegacy();
-if (out.stdout !== "") {
-  assert.fail(out.stdout);
-} else {
-  assert.equal(
-    normalizeNewlines(out.stderr),
-    [
-      'File "rescript.json", line 1',
-      "Error: package weird not found or built",
-      "- Did you install it?",
-      "",
-    ].join("\n"),
-  );
-}
+const out = await execBuild();
+assert.notEqual(out.status, 0);
+assert.match(out.stderr, /could not build package tree/i);
+assert.match(out.stderr, /dependency 'weird'/i);
+await execClean();
diff --git a/tests/build_tests/weird_devdeps/input.js b/tests/build_tests/weird_devdeps/input.js
index cc30a015b8..d98217346b 100644
--- a/tests/build_tests/weird_devdeps/input.js
+++ b/tests/build_tests/weird_devdeps/input.js
@@ -1,22 +1,12 @@
 // @ts-check
 
 import * as assert from "node:assert";
-import * as os from "node:os";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-const out = await execBuildLegacy();
-if (out.stdout !== "") {
-  assert.fail(out.stdout);
-} else {
-  assert.equal(
-    out.stderr,
-    [
-      'File "rescript.json", line 1',
-      "Error: package weird not found or built",
-      "- Did you install it?",
-      "",
-    ].join(os.EOL),
-  );
-}
+const out = await execBuild();
+assert.notEqual(out.status, 0);
+assert.match(out.stderr, /could not build package tree/i);
+assert.match(out.stderr, /dependency 'weird'/i);
+await execClean();
diff --git a/tests/build_tests/weird_names/input.js b/tests/build_tests/weird_names/input.js
index 92fcaf7f26..8eb69b1529 100644
--- a/tests/build_tests/weird_names/input.js
+++ b/tests/build_tests/weird_names/input.js
@@ -4,9 +4,9 @@ import * as assert from "node:assert";
 import * as path from "node:path";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
-const out = await execBuildLegacy();
+const out = await execBuild();
 
 if (out.stderr !== "") {
   assert.fail(out.stderr);
@@ -24,6 +24,7 @@ const files = [
 
 for (const f of files) {
   const { name } = path.parse(f);
-  const mod = await import(`./lib/es6/src/${name}.js`);
+  const mod = await import(`./src/${name}.js`);
   assert.deepEqual(mod.a, 1);
 }
+await execClean();
diff --git a/tests/build_tests/weird_names_not_found_bug/input.js b/tests/build_tests/weird_names_not_found_bug/input.js
index 9861ed7731..ed8ab223c6 100644
--- a/tests/build_tests/weird_names_not_found_bug/input.js
+++ b/tests/build_tests/weird_names_not_found_bug/input.js
@@ -1,14 +1,11 @@
 import * as assert from "node:assert";
+import { stripVTControlCharacters } from "node:util";
 import { setup } from "#dev/process";
 
-const { execBuildLegacy } = await setup(import.meta.dirname);
+const { execBuild, execClean } = await setup(import.meta.dirname);
 
-const out = await execBuildLegacy();
+const out = await execBuild();
+const stderr = stripVTControlCharacters(out.stderr);
 
-if (out.stderr !== "") {
-  assert.fail(out.stderr);
-}
-
-if (!out.stdout.includes(`The module or file Demo can't be found.`)) {
-  assert.fail(out.stdout);
-}
+assert.ok(stderr.includes(`The module or file Demo can't be found.`));
+await execClean();
diff --git a/tests/build_tests/x-y/input.js b/tests/build_tests/x-y/input.js
index 50a4ceabd1..dd8449f36b 100644
--- a/tests/build_tests/x-y/input.js
+++ b/tests/build_tests/x-y/input.js
@@ -2,6 +2,7 @@
 
 import { setup } from "#dev/process";
 
-const { execBuild } = setup(import.meta.dirname);
+const { execBuild, execClean } = setup(import.meta.dirname);
 
 await execBuild();
+await execClean();
diff --git a/tests/build_tests/xpkg/input.js b/tests/build_tests/xpkg/input.js
deleted file mode 100644
index 2d745b93b8..0000000000
--- a/tests/build_tests/xpkg/input.js
+++ /dev/null
@@ -1,9 +0,0 @@
-// @ts-check
-
-import * as assert from "node:assert";
-import { setup } from "#dev/process";
-
-const { execBuildLegacy } = await setup(import.meta.dirname);
-
-const output = await execBuildLegacy(["-regen"]);
-assert.match(output.stderr, /reserved package name/);
diff --git a/tests/build_tests/xpkg/rescript.json b/tests/build_tests/xpkg/rescript.json
deleted file mode 100644
index 50b8ac6da2..0000000000
--- a/tests/build_tests/xpkg/rescript.json
+++ /dev/null
@@ -1,4 +0,0 @@
-{
-  "name": "_",
-  "sources": "."
-}