diff --git a/tests/bundle_test/verify_flag_aquery.sh b/tests/bundle_test/verify_flag_aquery.sh
index bf9658f..da52435 100755
--- a/tests/bundle_test/verify_flag_aquery.sh
+++ b/tests/bundle_test/verify_flag_aquery.sh
@@ -6,40 +6,7 @@ script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd -P)"
 source "${script_dir}/../nested_bazel_test.sh"
 setup_nested_bazel_cmd
 
-find_workspace_root() {
-  local candidate
-  local module_path
-  local search_dir
-
-  for candidate in \
-    "${TEST_SRCDIR:-}/${TEST_WORKSPACE:-}" \
-    "${TEST_SRCDIR:-}/_main"; do
-    if [[ -n ${candidate} && -f "${candidate}/MODULE.bazel" ]]; then
-      printf '%s\n' "${candidate}"
-      return 0
-    fi
-  done
-
-  if [[ -n ${TEST_SRCDIR:-} ]]; then
-    module_path="$(find "${TEST_SRCDIR}" -maxdepth 3 -name MODULE.bazel -print -quit 2>/dev/null || true)"
-    if [[ -n ${module_path} ]]; then
-      dirname "${module_path}"
-      return 0
-    fi
-  fi
-
-  search_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd -P)"
-  candidate="$(cd "${search_dir}/../.." && pwd -P)"
-  if [[ -f "${candidate}/MODULE.bazel" ]]; then
-    printf '%s\n' "${candidate}"
-    return 0
-  fi
-
-  echo "Unable to locate rules_bun workspace root" >&2
-  exit 1
-}
-
-rules_bun_root="$(find_workspace_root)"
+rules_bun_root="$(find_nested_bazel_workspace_root "${BASH_SOURCE[0]}")"
 
 cleanup() {
   local status="$1"
diff --git a/tests/bundle_test/verify_sourcemap_shape.sh b/tests/bundle_test/verify_sourcemap_shape.sh
index 60865ac..34fa101 100755
--- a/tests/bundle_test/verify_sourcemap_shape.sh
+++ b/tests/bundle_test/verify_sourcemap_shape.sh
@@ -6,40 +6,7 @@ script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd -P)"
 source "${script_dir}/../nested_bazel_test.sh"
 setup_nested_bazel_cmd
 
-find_workspace_root() {
-  local candidate
-  local module_path
-  local search_dir
-
-  for candidate in \
-    "${TEST_SRCDIR:-}/${TEST_WORKSPACE:-}" \
-    "${TEST_SRCDIR:-}/_main"; do
-    if [[ -n ${candidate} && -f "${candidate}/MODULE.bazel" ]]; then
-      printf '%s\n' "${candidate}"
-      return 0
-    fi
-  done
-
-  if [[ -n ${TEST_SRCDIR:-} ]]; then
-    module_path="$(find "${TEST_SRCDIR}" -maxdepth 3 -name MODULE.bazel -print -quit 2>/dev/null || true)"
-    if [[ -n ${module_path} ]]; then
-      dirname "${module_path}"
-      return 0
-    fi
-  fi
-
-  search_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd -P)"
-  candidate="$(cd "${search_dir}/../.." && pwd -P)"
-  if [[ -f "${candidate}/MODULE.bazel" ]]; then
-    printf '%s\n' "${candidate}"
-    return 0
-  fi
-
-  echo "Unable to locate rules_bun workspace root" >&2
-  exit 1
-}
-
-rules_bun_root="$(find_workspace_root)"
+rules_bun_root="$(find_nested_bazel_workspace_root "${BASH_SOURCE[0]}")"
 
 cleanup() {
   local status="$1"
diff --git a/tests/install_test/lifecycle_scripts.sh b/tests/install_test/lifecycle_scripts.sh
index bd85d90..115678a 100755
--- a/tests/install_test/lifecycle_scripts.sh
+++ b/tests/install_test/lifecycle_scripts.sh
@@ -8,7 +8,7 @@ setup_nested_bazel_cmd
 
 bun_path="$1"
 
-rules_bun_root="$(cd "${script_dir}/../.." && pwd -P)"
+rules_bun_root="$(find_nested_bazel_workspace_root "${BASH_SOURCE[0]}")"
 
 workdir="$(mktemp -d)"
 cleanup() {
diff --git a/tests/install_test/repeatability.sh b/tests/install_test/repeatability.sh
index 64865f5..f437274 100755
--- a/tests/install_test/repeatability.sh
+++ b/tests/install_test/repeatability.sh
@@ -8,7 +8,7 @@ setup_nested_bazel_cmd
 
 bun_path="$1"
 
-rules_bun_root="$(cd "${script_dir}/../.." && pwd -P)"
+rules_bun_root="$(find_nested_bazel_workspace_root "${BASH_SOURCE[0]}")"
 
 workdir="$(mktemp -d)"
 cleanup() {
diff --git a/tests/install_test/workspace_parity.sh b/tests/install_test/workspace_parity.sh
index 99f6f60..c66b1e5 100755
--- a/tests/install_test/workspace_parity.sh
+++ b/tests/install_test/workspace_parity.sh
@@ -8,7 +8,7 @@ setup_nested_bazel_cmd
 
 bun_path="${1:-bun}"
 
-rules_bun_root="$(cd "${script_dir}/../.." && pwd -P)"
+rules_bun_root="$(find_nested_bazel_workspace_root "${BASH_SOURCE[0]}")"
 
 workdir="$(mktemp -d)"
 cleanup() {
diff --git a/tests/nested_bazel_test.sh b/tests/nested_bazel_test.sh
index a9af815..b621c72 100644
--- a/tests/nested_bazel_test.sh
+++ b/tests/nested_bazel_test.sh
@@ -1,24 +1,108 @@
 #!/usr/bin/env bash
 
 setup_nested_bazel_cmd() {
-  if command -v bazel >/dev/null 2>&1; then
-    bazel_cmd=(bazel)
-  elif command -v bazelisk >/dev/null 2>&1; then
-    bazel_cmd=(bazelisk)
+  local bazel_bin
+  local nested_bazel_base
+  local -a scrubbed_env_vars
+
+  if bazel_bin="$(command -v bazel 2>/dev/null)"; then
+    :
+  elif bazel_bin="$(command -v bazelisk 2>/dev/null)"; then
+    :
   else
     echo "bazel or bazelisk is required on PATH" >&2
     exit 1
   fi
+
+  nested_bazel_base="${TEST_TMPDIR:-${TMPDIR:-/tmp}}/rules_bun_nested_bazel"
+  mkdir -p "${nested_bazel_base}"
+  nested_bazel_root="$(mktemp -d "${nested_bazel_base}/session.XXXXXX")"
+  mkdir -p "${nested_bazel_root}/tmp"
+
+  scrubbed_env_vars=(
+    BAZEL_TEST
+    BUILD_EXECROOT
+    COVERAGE_DIR
+    GTEST_OUTPUT
+    GTEST_SHARD_INDEX
+    GTEST_SHARD_STATUS_FILE
+    GTEST_TMP_DIR
+    GTEST_TOTAL_SHARDS
+    JAVA_RUNFILES
+    PYTHON_RUNFILES
+    RUNFILES_DIR
+    RUNFILES_MANIFEST_FILE
+    RUNFILES_MANIFEST_ONLY
+    TEST_BINARY
+    TEST_INFRASTRUCTURE_FAILURE_FILE
+    TEST_LOGSPLITTER_OUTPUT_FILE
+    TEST_PREMATURE_EXIT_FILE
+    TEST_SHARD_INDEX
+    TEST_SHARD_STATUS_FILE
+    TEST_SRCDIR
+    TEST_TARGET
+    TEST_TMPDIR
+    TEST_TOTAL_SHARDS
+    TEST_UNDECLARED_OUTPUTS_ANNOTATIONS
+    TEST_UNDECLARED_OUTPUTS_ANNOTATIONS_DIR
+    TEST_UNDECLARED_OUTPUTS_DIR
+    TEST_UNDECLARED_OUTPUTS_MANIFEST
+    TEST_UNDECLARED_OUTPUTS_ZIP
+    TEST_UNUSED_RUNFILES_LOG_FILE
+    TEST_WARNINGS_OUTPUT_FILE
+    XML_OUTPUT_FILE
+  )
+
+  nested_bazel_env=(env)
+  for env_var in "${scrubbed_env_vars[@]}"; do
+    nested_bazel_env+=("-u" "${env_var}")
+  done
+  nested_bazel_env+=("TMPDIR=${nested_bazel_root}/tmp")
+
+  bazel_cmd=(
+    "${nested_bazel_env[@]}"
+    "${bazel_bin}"
+    "--batch"
+    "--ignore_all_rc_files"
+    "--output_user_root=${nested_bazel_root}/output_user_root"
+  )
+}
+
+find_nested_bazel_workspace_root() {
+  local script_path="${1:-${BASH_SOURCE[0]}}"
+  local candidate
+  local script_dir
+
+  for candidate in \
+    "${TEST_SRCDIR:-}/${TEST_WORKSPACE:-}" \
+    "${TEST_SRCDIR:-}/_main"; do
+    if [[ -n ${candidate} && -f "${candidate}/MODULE.bazel" ]]; then
+      printf '%s\n' "${candidate}"
+      return 0
+    fi
+  done
+
+  script_dir="$(cd "$(dirname "${script_path}")" && pwd -P)"
+  candidate="$(cd "${script_dir}/../.." && pwd -P)"
+  if [[ -f "${candidate}/MODULE.bazel" ]]; then
+    printf '%s\n' "${candidate}"
+    return 0
+  fi
+
+  echo "Unable to locate rules_bun workspace root" >&2
+  exit 1
 }
 
 shutdown_nested_bazel_workspace() {
   local workspace_dir="${1:-}"
-  if [[ -z ${workspace_dir} || ! -d ${workspace_dir} ]]; then
-    return 0
+  if [[ -n ${workspace_dir} && -d ${workspace_dir} ]]; then
+    (
+      cd "${workspace_dir}"
+      "${bazel_cmd[@]}" shutdown >/dev/null 2>&1
+    ) || true
   fi
 
-  (
-    cd "${workspace_dir}"
-    "${bazel_cmd[@]}" shutdown >/dev/null 2>&1
-  ) || true
+  if [[ -n ${nested_bazel_root:-} && -d ${nested_bazel_root} ]]; then
+    rm -rf "${nested_bazel_root}"
+  fi
 }
diff --git a/tests/npm_compat_test/npm_translate_lock_workspace_test.sh b/tests/npm_compat_test/npm_translate_lock_workspace_test.sh
index fb1ccff..0a54fa8 100755
--- a/tests/npm_compat_test/npm_translate_lock_workspace_test.sh
+++ b/tests/npm_compat_test/npm_translate_lock_workspace_test.sh
@@ -8,7 +8,7 @@ script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd -P)"
 source "${script_dir}/../nested_bazel_test.sh"
 setup_nested_bazel_cmd
 
-rules_bun_root="$(cd "${script_dir}/../.." && pwd -P)"
+rules_bun_root="$(find_nested_bazel_workspace_root "${BASH_SOURCE[0]}")"
 
 workdir="$(mktemp -d)"
 cleanup() {