diff --git a/components/servo/Cargo.lock b/components/servo/Cargo.lock
index 21b1955664d..a984dcf45a4 100644
--- a/components/servo/Cargo.lock
+++ b/components/servo/Cargo.lock
@@ -8,18 +8,22 @@ dependencies = [
  "devtools 0.0.1",
  "devtools_traits 0.0.1",
  "gfx 0.0.1",
+ "gfx_tests 0.0.1",
  "glutin_app 0.0.1",
  "layout 0.0.1",
  "msg 0.0.1",
  "net 0.0.1",
+ "net_tests 0.0.1",
  "net_traits 0.0.1",
  "png 0.1.0 (git+https://github.com/servo/rust-png)",
  "profile 0.0.1",
  "script 0.0.1",
+ "script_tests 0.0.1",
+ "style_tests 0.0.1",
  "time 0.1.19 (registry+https://github.com/rust-lang/crates.io-index)",
- "unit_tests 0.0.1",
  "url 0.2.23 (registry+https://github.com/rust-lang/crates.io-index)",
  "util 0.0.1",
+ "util_tests 0.0.1",
  "webdriver_server 0.0.1",
 ]
 
@@ -346,6 +350,13 @@ dependencies = [
  "util 0.0.1",
 ]
 
+[[package]]
+name = "gfx_tests"
+version = "0.0.1"
+dependencies = [
+ "gfx 0.0.1",
+]
+
 [[package]]
 name = "gl_common"
 version = "0.0.4"
@@ -661,6 +672,19 @@ dependencies = [
  "util 0.0.1",
 ]
 
+[[package]]
+name = "net_tests"
+version = "0.0.1"
+dependencies = [
+ "cookie 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)",
+ "hyper 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "net 0.0.1",
+ "net_traits 0.0.1",
+ "profile 0.0.1",
+ "url 0.2.23 (registry+https://github.com/rust-lang/crates.io-index)",
+ "util 0.0.1",
+]
+
 [[package]]
 name = "net_traits"
 version = "0.0.1"
@@ -824,6 +848,13 @@ dependencies = [
  "uuid 0.1.11 (git+https://github.com/rust-lang/uuid)",
 ]
 
+[[package]]
+name = "script_tests"
+version = "0.0.1"
+dependencies = [
+ "script 0.0.1",
+]
+
 [[package]]
 name = "script_traits"
 version = "0.0.1"
@@ -905,6 +936,20 @@ dependencies = [
  "util 0.0.1",
 ]
 
+[[package]]
+name = "style_tests"
+version = "0.0.1"
+dependencies = [
+ "cssparser 0.2.0 (git+https://github.com/servo/rust-cssparser)",
+ "geom 0.1.0 (git+https://github.com/servo/rust-geom)",
+ "selectors 0.1.0 (git+https://github.com/servo/rust-selectors)",
+ "string_cache 0.0.0 (git+https://github.com/servo/string-cache)",
+ "string_cache_plugin 0.0.0 (git+https://github.com/servo/string-cache)",
+ "style 0.0.1",
+ "url 0.2.23 (registry+https://github.com/rust-lang/crates.io-index)",
+ "util 0.0.1",
+]
+
 [[package]]
 name = "task_info"
 version = "0.0.1"
@@ -928,27 +973,6 @@ name = "unicase"
 version = "0.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "unit_tests"
-version = "0.0.1"
-dependencies = [
- "cookie 0.1.14 (registry+https://github.com/rust-lang/crates.io-index)",
- "cssparser 0.2.0 (git+https://github.com/servo/rust-cssparser)",
- "geom 0.1.0 (git+https://github.com/servo/rust-geom)",
- "gfx 0.0.1",
- "hyper 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "net 0.0.1",
- "net_traits 0.0.1",
- "profile 0.0.1",
- "script 0.0.1",
- "selectors 0.1.0 (git+https://github.com/servo/rust-selectors)",
- "string_cache 0.0.0 (git+https://github.com/servo/string-cache)",
- "string_cache_plugin 0.0.0 (git+https://github.com/servo/string-cache)",
- "style 0.0.1",
- "url 0.2.23 (registry+https://github.com/rust-lang/crates.io-index)",
- "util 0.0.1",
-]
-
 [[package]]
 name = "url"
 version = "0.2.23"
@@ -987,6 +1011,14 @@ dependencies = [
  "time 0.1.19 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "util_tests"
+version = "0.0.1"
+dependencies = [
+ "geom 0.1.0 (git+https://github.com/servo/rust-geom)",
+ "util 0.0.1",
+]
+
 [[package]]
 name = "uuid"
 version = "0.1.11"
diff --git a/components/servo/Cargo.toml b/components/servo/Cargo.toml
index f8d3fa3aa3e..24ab504b303 100644
--- a/components/servo/Cargo.toml
+++ b/components/servo/Cargo.toml
@@ -16,8 +16,20 @@ test = false
 doc = false
 bench = false
 
-[dev-dependencies.unit_tests]
-path = "../../tests/unit"
+[dev-dependencies.gfx_tests]
+path = "../../tests/unit/gfx"
+
+[dev-dependencies.net_tests]
+path = "../../tests/unit/net"
+
+[dev-dependencies.script_tests]
+path = "../../tests/unit/script"
+
+[dev-dependencies.style_tests]
+path = "../../tests/unit/style"
+
+[dev-dependencies.util_tests]
+path = "../../tests/unit/util"
 
 [[test]]
 name = "reftest"
diff --git a/python/servo/testing_commands.py b/python/servo/testing_commands.py
index b93d3689700..81361b0081f 100644
--- a/python/servo/testing_commands.py
+++ b/python/servo/testing_commands.py
@@ -101,17 +101,26 @@ class MachCommands(CommandBase):
     @Command('test-unit',
              description='Run unit tests',
              category='testing')
+    @CommandArgument('--package', '-p', default=None, help="Specific package to test")
     @CommandArgument('test_name', nargs=argparse.REMAINDER,
                      help="Only run tests that match this pattern")
-    def test_unit(self, test_name=None, component=None, package=None):
+    def test_unit(self, test_name=None, package=None):
         if test_name is None:
             test_name = []
 
         self.ensure_bootstrapped()
 
-        return 0 != subprocess.call(
-            ["cargo", "test", "-p", "unit_tests"]
-            + test_name, env=self.build_env(), cwd=self.servo_crate())
+        if package:
+            packages = [package]
+        else:
+            packages = os.listdir(path.join(self.context.topdir, "tests", "unit"))
+
+        for crate in packages:
+            result = subprocess.call(
+                ["cargo", "test", "-p", "%s_tests" % crate] + test_name,
+                env=self.build_env(), cwd=self.servo_crate())
+            if result != 0:
+                return result
 
     @Command('test-ref',
              description='Run the reference tests',
diff --git a/tests/unit/gfx/Cargo.toml b/tests/unit/gfx/Cargo.toml
new file mode 100644
index 00000000000..24e43ff3def
--- /dev/null
+++ b/tests/unit/gfx/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "gfx_tests"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+
+[lib]
+name = "gfx_tests"
+path = "lib.rs"
+doctest = false
+
+[dependencies.gfx]
+path = "../../../components/gfx"
diff --git a/tests/unit/gfx/mod.rs b/tests/unit/gfx/lib.rs
similarity index 81%
rename from tests/unit/gfx/mod.rs
rename to tests/unit/gfx/lib.rs
index 4d160f2a8dc..9a5040b6fe1 100644
--- a/tests/unit/gfx/mod.rs
+++ b/tests/unit/gfx/lib.rs
@@ -2,4 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-mod text_util;
+extern crate gfx;
+
+#[cfg(test)] mod text_util;
diff --git a/tests/unit/net/Cargo.toml b/tests/unit/net/Cargo.toml
new file mode 100644
index 00000000000..390d6f8ba01
--- /dev/null
+++ b/tests/unit/net/Cargo.toml
@@ -0,0 +1,26 @@
+[package]
+name = "net_tests"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+
+[lib]
+name = "net_tests"
+path = "lib.rs"
+doctest = false
+
+[dependencies.net]
+path = "../../../components/net"
+
+[dependencies.net_traits]
+path = "../../../components/net_traits"
+
+[dependencies.profile]
+path = "../../../components/profile"
+
+[dependencies.util]
+path = "../../../components/util"
+
+[dependencies]
+cookie = "*"
+hyper = "*"
+url = "*"
diff --git a/tests/unit/net/lib.rs b/tests/unit/net/lib.rs
new file mode 100644
index 00000000000..d38edca2617
--- /dev/null
+++ b/tests/unit/net/lib.rs
@@ -0,0 +1,17 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#![cfg_attr(test, feature(net, alloc, path, io))]
+
+extern crate net;
+extern crate net_traits;
+extern crate profile;
+extern crate url;
+extern crate util;
+
+#[cfg(test)] mod cookie;
+#[cfg(test)] mod data_loader;
+#[cfg(test)] mod image_cache_task;
+#[cfg(test)] mod mime_classifier;
+#[cfg(test)] mod resource_task;
diff --git a/tests/unit/net/mime_classifier.rs b/tests/unit/net/mime_classifier.rs
index e56e76d1cb3..8bba57290c5 100644
--- a/tests/unit/net/mime_classifier.rs
+++ b/tests/unit/net/mime_classifier.rs
@@ -23,7 +23,7 @@ fn read_file(path: &path::Path) -> io::Result<Vec<u8>> {
 fn test_sniff_mp4_matcher() {
     let matcher = Mp4Matcher;
 
-    let p = PathBuf::new("../../tests/unit/net/parsable_mime/video/mp4/test.mp4");
+    let p = PathBuf::new("parsable_mime/video/mp4/test.mp4");
     let read_result = read_file(&p);
 
     match read_result {
@@ -43,7 +43,7 @@ fn test_sniff_full(filename_orig: &path::Path,type_string: &str,subtype_string:
     let current_working_directory = env::current_dir().unwrap();
     println!("The current directory is {}", current_working_directory.display());
 
-    let mut filename = PathBuf::new("../../tests/unit/net/parsable_mime/");
+    let mut filename = PathBuf::new("parsable_mime/");
     filename.push(filename_orig);
 
     let classifier = MIMEClassifier::new();
diff --git a/tests/unit/net/mod.rs b/tests/unit/net/mod.rs
deleted file mode 100644
index 0d304270422..00000000000
--- a/tests/unit/net/mod.rs
+++ /dev/null
@@ -1,9 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-mod cookie;
-mod data_loader;
-mod image_cache_task;
-mod mime_classifier;
-mod resource_task;
diff --git a/tests/unit/script/Cargo.toml b/tests/unit/script/Cargo.toml
new file mode 100644
index 00000000000..759e0581545
--- /dev/null
+++ b/tests/unit/script/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "script_tests"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+
+[lib]
+name = "script_tests"
+path = "lib.rs"
+doctest = false
+
+[dependencies.script]
+path = "../../../components/script"
diff --git a/tests/unit/script/mod.rs b/tests/unit/script/lib.rs
similarity index 65%
rename from tests/unit/script/mod.rs
rename to tests/unit/script/lib.rs
index 1631a9adc8c..3073fcb8588 100644
--- a/tests/unit/script/mod.rs
+++ b/tests/unit/script/lib.rs
@@ -2,5 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-#[cfg(target_pointer_width = "64")] mod size_of;
-mod textinput;
+extern crate script;
+
+#[cfg(all(test, target_pointer_width = "64"))] mod size_of;
+#[cfg(test)] mod textinput;
diff --git a/tests/unit/Cargo.toml b/tests/unit/style/Cargo.toml
similarity index 57%
rename from tests/unit/Cargo.toml
rename to tests/unit/style/Cargo.toml
index 3c3c80a3e4b..64e34f2bd03 100644
--- a/tests/unit/Cargo.toml
+++ b/tests/unit/style/Cargo.toml
@@ -1,50 +1,33 @@
 [package]
-name = "unit_tests"
+name = "style_tests"
 version = "0.0.1"
 authors = ["The Servo Project Developers"]
 
 [lib]
-name = "unit_tests"
+name = "style_tests"
 path = "lib.rs"
 doctest = false
 
-[dependencies.util]
-path = "../../components/util"
-
-[dependencies.gfx]
-path = "../../components/gfx"
-
-[dependencies.net]
-path = "../../components/net"
-
-[dependencies.net_traits]
-path = "../../components/net_traits"
-
-[dependencies.profile]
-path = "../../components/profile"
-
 [dependencies.style]
-path = "../../components/style"
+path = "../../../components/style"
 
-[dependencies.script]
-path = "../../components/script"
-
-[dependencies.geom]
-git = "https://github.com/servo/rust-geom"
-
-[dependencies.cssparser]
-git = "https://github.com/servo/rust-cssparser"
-
-[dependencies.selectors]
-git = "https://github.com/servo/rust-selectors"
-
-[dependencies.string_cache]
-git = "https://github.com/servo/string-cache"
+[dependencies.util]
+path = "../../../components/util"
 
 [dependencies.string_cache_plugin]
 git = "https://github.com/servo/string-cache"
 
+[dependencies.string_cache]
+git = "https://github.com/servo/string-cache"
+
+[dependencies.geom]
+git = "https://github.com/servo/rust-geom"
+
+[dependencies.selectors]
+git = "https://github.com/servo/rust-selectors"
+
+[dependencies.cssparser]
+git = "https://github.com/servo/rust-cssparser"
+
 [dependencies]
-cookie = "*"
 url = "*"
-hyper = "0.3"
diff --git a/tests/unit/lib.rs b/tests/unit/style/lib.rs
similarity index 50%
rename from tests/unit/lib.rs
rename to tests/unit/style/lib.rs
index 05542a17840..9e379d1336b 100644
--- a/tests/unit/lib.rs
+++ b/tests/unit/style/lib.rs
@@ -3,25 +3,26 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #![feature(plugin)]
-#![cfg_attr(test, feature(net, alloc, path, io))]
-
 #![plugin(string_cache_plugin)]
 
 extern crate cssparser;
 extern crate geom;
-extern crate gfx;
-extern crate net;
-extern crate net_traits;
-extern crate profile;
-extern crate script;
 extern crate selectors;
 extern crate string_cache;
 extern crate style;
-extern crate util;
 extern crate url;
+extern crate util;
 
-#[cfg(test)] #[path="gfx/mod.rs"] mod gfx_tests;
-#[cfg(test)] #[path="net/mod.rs"] mod net_tests;
-#[cfg(test)] #[path="script/mod.rs"] mod script_tests;
-#[cfg(test)] #[path="style/mod.rs"] mod style_tests;
-#[cfg(test)] #[path="util/mod.rs"] mod util_tests;
+
+#[cfg(test)] mod stylesheets;
+#[cfg(test)] mod media_queries;
+
+#[cfg(test)] mod writing_modes {
+    use util::logical_geometry::WritingMode;
+    use style::properties::{INITIAL_VALUES, get_writing_mode};
+
+    #[test]
+    fn initial_writing_mode_is_empty() {
+        assert_eq!(get_writing_mode(INITIAL_VALUES.get_inheritedbox()), WritingMode::empty())
+    }
+}
diff --git a/tests/unit/style/mod.rs b/tests/unit/style/mod.rs
deleted file mode 100644
index a2af201f7c3..00000000000
--- a/tests/unit/style/mod.rs
+++ /dev/null
@@ -1,16 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-use util::logical_geometry::WritingMode;
-use style::properties::{INITIAL_VALUES, get_writing_mode};
-
-
-mod stylesheets;
-mod media_queries;
-
-
-#[test]
-fn initial_writing_mode_is_empty() {
-    assert_eq!(get_writing_mode(INITIAL_VALUES.get_inheritedbox()), WritingMode::empty())
-}
diff --git a/tests/unit/util/Cargo.toml b/tests/unit/util/Cargo.toml
new file mode 100644
index 00000000000..48df1b5aedb
--- /dev/null
+++ b/tests/unit/util/Cargo.toml
@@ -0,0 +1,15 @@
+[package]
+name = "util_tests"
+version = "0.0.1"
+authors = ["The Servo Project Developers"]
+
+[lib]
+name = "util_tests"
+path = "lib.rs"
+doctest = false
+
+[dependencies.util]
+path = "../../../components/util"
+
+[dependencies.geom]
+git = "https://github.com/servo/rust-geom"
diff --git a/tests/unit/util/mod.rs b/tests/unit/util/lib.rs
similarity index 59%
rename from tests/unit/util/mod.rs
rename to tests/unit/util/lib.rs
index 756af732b67..07ce741d972 100644
--- a/tests/unit/util/mod.rs
+++ b/tests/unit/util/lib.rs
@@ -2,7 +2,10 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-mod cache;
-mod logical_geometry;
-mod task;
-mod vec;
+extern crate util;
+extern crate geom;
+
+#[cfg(test)] mod cache;
+#[cfg(test)] mod logical_geometry;
+#[cfg(test)] mod task;
+#[cfg(test)] mod vec;