diff --git a/zigux/tests/phase1_bench_build_contract.zig b/zigux/tests/phase1_bench_build_contract.zig
new file mode 100644
index 00000000000000..ad83c5999ebbe7
--- /dev/null
+++ b/zigux/tests/phase1_bench_build_contract.zig
@@ -0,0 +1,71 @@
+const std = @import("std");
+
+const build_source = @embedFile("phase1_bench_build.zig");
+
+fn expectContains(needle: []const u8) !void {
+    try std.testing.expect(std.mem.indexOf(u8, build_source, needle) != null);
+}
+
+fn expectOccurs(needle: []const u8, expected: usize) !void {
+    var cursor: usize = 0;
+    var count: usize = 0;
+    while (std.mem.indexOf(u8, build_source[cursor..], needle)) |offset| {
+        count += 1;
+        cursor += offset + needle.len;
+    }
+    try std.testing.expectEqual(expected, count);
+}
+
+fn expectOrdered(markers: []const []const u8) !void {
+    var cursor: usize = 0;
+    for (markers) |marker| {
+        const offset = std.mem.indexOf(u8, build_source[cursor..], marker) orelse return error.MissingBuildMarker;
+        cursor += offset + marker.len;
+    }
+}
+
+test "phase1 bench build gate keeps the current helper module packet" {
+    const helper_paths = [_][]const u8{
+        ".root_source_file = b.path(\"phase1_bench.zig\")",
+        ".root_source_file = b.path(\"../../tools/lib/find_bit.zig\")",
+        ".root_source_file = b.path(\"../../tools/lib/bitmap.zig\")",
+        ".root_source_file = b.path(\"../../tools/lib/string.zig\")",
+        ".root_source_file = b.path(\"../../tools/lib/hweight.zig\")",
+        ".root_source_file = b.path(\"../../tools/lib/list_sort.zig\")",
+        ".root_source_file = b.path(\"../../tools/lib/rbtree.zig\")",
+    };
+    for (helper_paths) |path_marker| {
+        try expectContains(path_marker);
+    }
+
+    const imports = [_][]const u8{
+        "bitmap_module.addImport(\"find_bit\", find_bit_module);",
+        "root_module.addImport(\"bitmap\", bitmap_module);",
+        "root_module.addImport(\"find_bit\", find_bit_module);",
+        "root_module.addImport(\"hweight\", hweight_module);",
+        "root_module.addImport(\"list_sort\", list_sort_module);",
+        "root_module.addImport(\"rbtree\", rbtree_module);",
+        "root_module.addImport(\"string\", string_module);",
+    };
+    for (imports) |import_marker| {
+        try expectContains(import_marker);
+    }
+}
+
+test "phase1 bench build gate keeps bench, test, and default step wiring" {
+    try expectContains(".name = \"phase1-bench\"");
+    try expectContains("const run_bench = b.addRunArtifact(exe);");
+    try expectOccurs("b.step(", 2);
+    try expectOccurs("&run_bench.step", 2);
+
+    try expectOrdered(&[_][]const u8{
+        "const run_bench = b.addRunArtifact(exe);",
+        "const bench_step = b.step(",
+        "\"bench\"",
+        "bench_step.dependOn(&run_bench.step);",
+        "const test_step = b.step(",
+        "\"test\"",
+        "test_step.dependOn(&run_bench.step);",
+        "b.default_step.dependOn(test_step);",
+    });
+}