diff --git a/tests/specs/bench/filter_group_header/main.out b/tests/specs/bench/filter_group_header/main.out
index e8b11299ca..efe157f6cb 100644
--- a/tests/specs/bench/filter_group_header/main.out
+++ b/tests/specs/bench/filter_group_header/main.out
@@ -7,7 +7,7 @@ benchmark      time (avg)        iter/s             (min … max)       p75
 --------------------------------------------------------------- -----------------------------
 
 group G1
-G1-B          [WILDCARD]
+G1-B         [WILDCARD]
 
 group G2
-G2-B          [WILDCARD]
\ No newline at end of file
+G2-B         [WILDCARD]
\ No newline at end of file
diff --git a/tests/specs/check/cjs_default_export/__test__.jsonc b/tests/specs/check/cjs_default_export/__test__.jsonc
index 852942826b..a991c6eed4 100644
--- a/tests/specs/check/cjs_default_export/__test__.jsonc
+++ b/tests/specs/check/cjs_default_export/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "npm",
   "args": "check main.ts",
   "output": "main.out",
   "exitCode": 1
diff --git a/tests/specs/jsr/deps/__test__.jsonc b/tests/specs/jsr/deps/__test__.jsonc
index 2528003b51..a8837a8b53 100644
--- a/tests/specs/jsr/deps/__test__.jsonc
+++ b/tests/specs/jsr/deps/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "jsr",
   "steps": [{
     "args": "run main.ts",
     "output": "main.out"
diff --git a/tests/specs/jsr/import_https_url/__test__.jsonc b/tests/specs/jsr/import_https_url/__test__.jsonc
index 597b8e009e..8ba999d8a6 100644
--- a/tests/specs/jsr/import_https_url/__test__.jsonc
+++ b/tests/specs/jsr/import_https_url/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "jsr",
   "steps": [{
     "args": "run -A analyzable.ts",
     "output": "analyzable.out",
diff --git a/tests/specs/jsr/jsx_with_no_pragmas/__test__.jsonc b/tests/specs/jsr/jsx_with_no_pragmas/__test__.jsonc
index c2a269ea64..7b5c5e1b67 100644
--- a/tests/specs/jsr/jsx_with_no_pragmas/__test__.jsonc
+++ b/tests/specs/jsr/jsx_with_no_pragmas/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "jsr",
   "args": "run main.ts",
   "output": "main.out",
   "exitCode": 1
diff --git a/tests/specs/jsr/jsx_with_pragmas/__test__.jsonc b/tests/specs/jsr/jsx_with_pragmas/__test__.jsonc
index a6fa5c7c3f..5517e693d6 100644
--- a/tests/specs/jsr/jsx_with_pragmas/__test__.jsonc
+++ b/tests/specs/jsr/jsx_with_pragmas/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "jsr",
   "args": "run main.ts",
   "output": "main.out"
 }
diff --git a/tests/specs/jsr/module_graph/__test__.jsonc b/tests/specs/jsr/module_graph/__test__.jsonc
index 2528003b51..a8837a8b53 100644
--- a/tests/specs/jsr/module_graph/__test__.jsonc
+++ b/tests/specs/jsr/module_graph/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "jsr",
   "steps": [{
     "args": "run main.ts",
     "output": "main.out"
diff --git a/tests/specs/jsr/no_module_graph/__test__.jsonc b/tests/specs/jsr/no_module_graph/__test__.jsonc
index b3915ecef7..6c89ccb547 100644
--- a/tests/specs/jsr/no_module_graph/__test__.jsonc
+++ b/tests/specs/jsr/no_module_graph/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "jsr",
   "steps": [{
     "args": "run main.ts",
     "output": "main.out"
diff --git a/tests/specs/jsr/no_unused_params/__test__.jsonc b/tests/specs/jsr/no_unused_params/__test__.jsonc
index 4192ad5dd5..981d99fba8 100644
--- a/tests/specs/jsr/no_unused_params/__test__.jsonc
+++ b/tests/specs/jsr/no_unused_params/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "jsr",
   "steps": [{
     "args": "check --all main.ts",
     "output": "main.out"
diff --git a/tests/specs/jsr/subset_type_graph/__test__.jsonc b/tests/specs/jsr/subset_type_graph/__test__.jsonc
index 85d04ed54d..d62e2283fa 100644
--- a/tests/specs/jsr/subset_type_graph/__test__.jsonc
+++ b/tests/specs/jsr/subset_type_graph/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "jsr",
   "args": "check --all main.ts",
   "output": "main.check.out",
   "exitCode": 1
diff --git a/tests/specs/jsr/version_not_found/__test__.jsonc b/tests/specs/jsr/version_not_found/__test__.jsonc
index 36335985fe..91d7523aff 100644
--- a/tests/specs/jsr/version_not_found/__test__.jsonc
+++ b/tests/specs/jsr/version_not_found/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "jsr",
   "args": "run -A main.ts",
   "output": "main.out",
   "exitCode": 1
diff --git a/tests/specs/mod.rs b/tests/specs/mod.rs
index 17263b8b9c..a8c13f99a9 100644
--- a/tests/specs/mod.rs
+++ b/tests/specs/mod.rs
@@ -101,15 +101,12 @@ fn run_test(test: &Test, diagnostic_logger: Rc<RefCell<Vec<u8>>>) {
     builder = builder.cwd(cwd.to_string_lossy());
   }
 
-  if let Some(base) = &metadata.base {
-    match base.as_str() {
-      "npm" => {
-        builder = builder.add_npm_env_vars();
-      }
-      "jsr" => {
-        builder = builder.add_jsr_env_vars().add_npm_env_vars();
-      }
-      _ => panic!("Unknown test base: {}", base),
+  match &metadata.base {
+    // todo(dsherret): add bases in the future as needed
+    Some(base) => panic!("Unknown test base: {}", base),
+    None => {
+      // by default add npm and jsr env vars
+      builder = builder.add_jsr_env_vars().add_npm_env_vars();
     }
   }
 
diff --git a/tests/specs/npm/check_pkg_json_import/__test__.jsonc b/tests/specs/npm/check_pkg_json_import/__test__.jsonc
index ce8e532802..77487e6b40 100644
--- a/tests/specs/npm/check_pkg_json_import/__test__.jsonc
+++ b/tests/specs/npm/check_pkg_json_import/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "npm",
   "args": "check --all main.ts",
   "output": "main.out"
 }
diff --git a/tests/specs/npm/conditional_exports/__test__.jsonc b/tests/specs/npm/conditional_exports/__test__.jsonc
index 72b058cbfb..57a8d89e44 100644
--- a/tests/specs/npm/conditional_exports/__test__.jsonc
+++ b/tests/specs/npm/conditional_exports/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "npm",
   "args": "run --allow-read main.js",
   "output": "main.out"
 }
diff --git a/tests/specs/npm/conditional_exports_node_modules_dir/__test__.jsonc b/tests/specs/npm/conditional_exports_node_modules_dir/__test__.jsonc
index 09ea8b23b2..757e1c4e0e 100644
--- a/tests/specs/npm/conditional_exports_node_modules_dir/__test__.jsonc
+++ b/tests/specs/npm/conditional_exports_node_modules_dir/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "npm",
   "tempDir": true,
   "args": "run --allow-read --node-modules-dir main.js",
   "output": "main.out"
diff --git a/tests/specs/npm/es_module/__test__.jsonc b/tests/specs/npm/es_module/__test__.jsonc
index f720a2bc08..7fd8c95e05 100644
--- a/tests/specs/npm/es_module/__test__.jsonc
+++ b/tests/specs/npm/es_module/__test__.jsonc
@@ -1,5 +1,4 @@
 {
-  "base": "npm",
   "steps": [{
     "args": "run --allow-read --allow-env main.js",
     "output": "main.out"