3 files changed, 29 insertions, 0 deletions
diff --git a/tests/specs/add/exiting_dev_deps/__test__.jsonc b/tests/specs/add/exiting_dev_deps/__test__.jsonc
new file mode 100644
index 000000000..8a6ef1a5f
--- /dev/null
+++ b/tests/specs/add/exiting_dev_deps/__test__.jsonc
@@ -0,0 +1,16 @@
+{
+  "tempDir": true,
+  "steps": [
+    {
+      "args": "add npm:@denotest/esm-basic",
+      "output": "[WILDCARD]"
+    },
+    {
+      "args": [
+        "eval",
+        "console.log(Deno.readTextFileSync('package.json').trim())"
+      ],
+      "output": "package.json.out"
+    }
+  ]
+}
diff --git a/tests/specs/add/exiting_dev_deps/package.json b/tests/specs/add/exiting_dev_deps/package.json
new file mode 100644
index 000000000..e7b8c5061
--- /dev/null
+++ b/tests/specs/add/exiting_dev_deps/package.json
@@ -0,0 +1,5 @@
+{
+  "devDependencies": {
+    "cowsay": "*"
+  }
+}
diff --git a/tests/specs/add/exiting_dev_deps/package.json.out b/tests/specs/add/exiting_dev_deps/package.json.out
new file mode 100644
index 000000000..9bff99bc2
--- /dev/null
+++ b/tests/specs/add/exiting_dev_deps/package.json.out
@@ -0,0 +1,8 @@
+{
+  "dependencies": {
+    "@denotest/esm-basic": "^1.0.0"
+  },
+  "devDependencies": {
+    "cowsay": "*"
+  }
+}