diff --git a/.gitignore b/.gitignore
index 1fbc882..3aa27e8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 /target
 result
 .direnv
+node_modules
diff --git a/src/workspaces.rs b/src/workspaces.rs
index 5b51e93..6a16360 100644
--- a/src/workspaces.rs
+++ b/src/workspaces.rs
@@ -13,14 +13,12 @@ use crate::{
 
 #[derive(Debug)]
 pub struct Workspaces {
-  kind: PackageManagerKind,
   pub packages: Vec<PathBuf>,
 }
 
 impl Workspaces {
   pub fn new(base_dir: PathBuf, kind: PackageManagerKind, patterns: Option<Vec<String>>) -> Self {
     Self {
-      kind: kind,
       packages: match &kind {
         PackageManagerKind::Npm => Workspaces::resolve_npm_workspaces(base_dir, patterns),
         PackageManagerKind::Bun => Workspaces::resolve_bun_workspaces(base_dir, patterns),
@@ -103,7 +101,6 @@ mod tests {
   fn test_new_each(case: NewTestCase) {
     let base_dir = case.input.0;
     let workspaces = Workspaces::new(base_dir.clone(), case.input.1, case.input.2);
-    assert_eq!(workspaces.kind, case.expected.kind);
     assert_eq!(
       workspaces.packages,
       case
@@ -117,6 +114,52 @@ mod tests {
 
   test_each_serial!(
     test_new,
+    "npm_evaluate_negate_patterns" => NewTestCase {
+      input: (
+        PathBuf::from("tests/fixtures/workspaces/npm"),
+        PackageManagerKind::Npm,
+        Some(vec![
+          String::from("packages/*"),
+          String::from("!packages/c"),
+        ]),
+      ),
+      expected: Workspaces {
+        packages: vec![
+          PathBuf::from("./packages/a"),
+          PathBuf::from("./packages/b"),
+        ],
+      },
+    },
+    "yarn_evaluate_negate_patterns" => NewTestCase {
+      input: (
+        PathBuf::from("tests/fixtures/workspaces/yarn"),
+        PackageManagerKind::Yarn,
+        Some(vec![
+          String::from("packages/*"),
+          String::from("!packages/c"),
+        ]),
+      ),
+      expected: Workspaces {
+        packages: vec![
+          PathBuf::from("./packages/a"),
+          PathBuf::from("./packages/b"),
+          PathBuf::from("./packages/c"),
+        ],
+      },
+    },
+    "pnpm_evaluate_negate_patterns" => NewTestCase {
+      input: (
+        PathBuf::from("tests/fixtures/workspaces/pnpm"),
+        PackageManagerKind::Pnpm,
+        None,
+      ),
+      expected: Workspaces {
+        packages: vec![
+          PathBuf::from("./packages/a"),
+          PathBuf::from("./packages/b"),
+        ],
+      },
+    },
     "bun" => NewTestCase {
       input: (
         PathBuf::from("tests/fixtures/workspaces/bun"),
@@ -127,7 +170,6 @@ mod tests {
         ]),
       ),
       expected: Workspaces {
-        kind: PackageManagerKind::Bun,
         packages: vec![
           PathBuf::from("./packages/a"),
           PathBuf::from("./packages/b"),
diff --git a/tests/fixtures/workspaces/bun/packages/b/.gitkeep b/tests/fixtures/workspaces/bun/packages/b/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/tests/fixtures/workspaces/npm/package-lock.json b/tests/fixtures/workspaces/npm/package-lock.json
new file mode 100644
index 0000000..4bd1921
--- /dev/null
+++ b/tests/fixtures/workspaces/npm/package-lock.json
@@ -0,0 +1,24 @@
+{
+  "name": "npm",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "dependencies": {
+        "typescript": "^5.3.3"
+      }
+    },
+    "node_modules/typescript": {
+      "version": "5.3.3",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.3.3.tgz",
+      "integrity": "sha512-pXWcraxM0uxAS+tN0AG/BF2TyqmHO014Z070UsJ+pFvYuRSq8KH8DmWpnbXe0pEPDHXZV3FcAbJkijJ5oNEnWw==",
+      "bin": {
+        "tsc": "bin/tsc",
+        "tsserver": "bin/tsserver"
+      },
+      "engines": {
+        "node": ">=14.17"
+      }
+    }
+  }
+}
diff --git a/tests/fixtures/workspaces/npm/package.json b/tests/fixtures/workspaces/npm/package.json
new file mode 100644
index 0000000..7c88992
--- /dev/null
+++ b/tests/fixtures/workspaces/npm/package.json
@@ -0,0 +1,5 @@
+{
+  "dependencies": {
+    "typescript": "^5.3.3"
+  }
+}
diff --git a/tests/fixtures/workspaces/bun/packages/b/package.json b/tests/fixtures/workspaces/npm/packages/a/package.json
similarity index 100%
rename from tests/fixtures/workspaces/bun/packages/b/package.json
rename to tests/fixtures/workspaces/npm/packages/a/package.json
diff --git a/tests/fixtures/workspaces/npm/packages/b/.gitkeep b/tests/fixtures/workspaces/npm/packages/b/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/tests/fixtures/workspaces/npm/packages/c/package.json b/tests/fixtures/workspaces/npm/packages/c/package.json
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/tests/fixtures/workspaces/npm/packages/c/package.json
@@ -0,0 +1 @@
+{}
diff --git a/tests/fixtures/workspaces/pnpm/package.json b/tests/fixtures/workspaces/pnpm/package.json
new file mode 100644
index 0000000..7c88992
--- /dev/null
+++ b/tests/fixtures/workspaces/pnpm/package.json
@@ -0,0 +1,5 @@
+{
+  "dependencies": {
+    "typescript": "^5.3.3"
+  }
+}
diff --git a/tests/fixtures/workspaces/pnpm/packages/a/package.json b/tests/fixtures/workspaces/pnpm/packages/a/package.json
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/tests/fixtures/workspaces/pnpm/packages/a/package.json
@@ -0,0 +1 @@
+{}
diff --git a/tests/fixtures/workspaces/pnpm/packages/b/.gitkeep b/tests/fixtures/workspaces/pnpm/packages/b/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/tests/fixtures/workspaces/pnpm/packages/c/package.json b/tests/fixtures/workspaces/pnpm/packages/c/package.json
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/tests/fixtures/workspaces/pnpm/packages/c/package.json
@@ -0,0 +1 @@
+{}
diff --git a/tests/fixtures/workspaces/pnpm/pnpm-lock.yaml b/tests/fixtures/workspaces/pnpm/pnpm-lock.yaml
new file mode 100644
index 0000000..87f14d5
--- /dev/null
+++ b/tests/fixtures/workspaces/pnpm/pnpm-lock.yaml
@@ -0,0 +1,25 @@
+lockfileVersion: '6.0'
+
+settings:
+  autoInstallPeers: true
+  excludeLinksFromLockfile: false
+
+importers:
+
+  .:
+    dependencies:
+      typescript:
+        specifier: ^5.3.3
+        version: 5.3.3
+
+  packages/a: {}
+
+  packages/b: {}
+
+packages:
+
+  /typescript@5.3.3:
+    resolution: {integrity: sha512-pXWcraxM0uxAS+tN0AG/BF2TyqmHO014Z070UsJ+pFvYuRSq8KH8DmWpnbXe0pEPDHXZV3FcAbJkijJ5oNEnWw==}
+    engines: {node: '>=14.17'}
+    hasBin: true
+    dev: false
diff --git a/tests/fixtures/workspaces/pnpm/pnpm-workspace.yaml b/tests/fixtures/workspaces/pnpm/pnpm-workspace.yaml
new file mode 100644
index 0000000..3c056ee
--- /dev/null
+++ b/tests/fixtures/workspaces/pnpm/pnpm-workspace.yaml
@@ -0,0 +1,3 @@
+packages:
+  - 'packages/*'
+  - '!packages/c'
diff --git a/tests/fixtures/workspaces/yarn/package.json b/tests/fixtures/workspaces/yarn/package.json
new file mode 100644
index 0000000..7c88992
--- /dev/null
+++ b/tests/fixtures/workspaces/yarn/package.json
@@ -0,0 +1,5 @@
+{
+  "dependencies": {
+    "typescript": "^5.3.3"
+  }
+}
diff --git a/tests/fixtures/workspaces/yarn/packages/a/package.json b/tests/fixtures/workspaces/yarn/packages/a/package.json
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/tests/fixtures/workspaces/yarn/packages/a/package.json
@@ -0,0 +1 @@
+{}
diff --git a/tests/fixtures/workspaces/yarn/packages/b/.gitkeep b/tests/fixtures/workspaces/yarn/packages/b/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/tests/fixtures/workspaces/yarn/packages/c/package.json b/tests/fixtures/workspaces/yarn/packages/c/package.json
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/tests/fixtures/workspaces/yarn/packages/c/package.json
@@ -0,0 +1 @@
+{}
diff --git a/tests/fixtures/workspaces/yarn/yarn.lock b/tests/fixtures/workspaces/yarn/yarn.lock
new file mode 100644
index 0000000..cd07bce
--- /dev/null
+++ b/tests/fixtures/workspaces/yarn/yarn.lock
@@ -0,0 +1,8 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
+typescript@^5.3.3:
+  version "5.3.3"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-5.3.3.tgz#b3ce6ba258e72e6305ba66f5c9b452aaee3ffe37"
+  integrity sha512-pXWcraxM0uxAS+tN0AG/BF2TyqmHO014Z070UsJ+pFvYuRSq8KH8DmWpnbXe0pEPDHXZV3FcAbJkijJ5oNEnWw==