diff --git a/README.md b/README.md
index 98286b8..1b23c38 100644
--- a/README.md
+++ b/README.md
@@ -145,10 +145,12 @@ As well as testing individual packages you can also test all packages found in v
 
 * `test_pipfile(<file-handle-or-string>)` - returns an IssueSet for all Python dependencies in a `Pipfile` 
 * `test_gemfilelock(<file-handle-or-string>)` - returns an IssueSet for all Ruby dependencies in a `Gemfile`
-* `test_packagejson(<file-handle-or-string>)` - returns an IssueSet for all Javascript dependencies in a `package.json` file 
+* `test_packagejson(<file-handle-or-string>, (<lock-file-handle-or-string>))` - returns an IssueSet for all Javascript dependencies in a `package.json` file. Optionally takes a `package.lock` file
 * `test_gradlefile(<file-handle-or-string>)` - returns an IssueSet for all dependencies in a `Gradlefile` 
 * `test_sbt(<file-handle-or-string>)` - returns an IssueSet for all dependencies defined in a `.sbt` file 
 * `test_pom(<file-handle-or-string>)` - returns an IssueSet for all dependencies in a Maven `pom.xml` file
+* `test_yarn(<file-handle-or-string>, <lock-file-handle-or-string>)` - returns an IssueSet for all dependencies in Yarn `package.json` and `yarn.lock` files
+* `test_composer(<file-handle-or-string>, <lock-file-handle-or-string>)` - returns an IssueSet for all dependencies in Composer `composer.json` and `composer.lock` files
 
 For example, here we are testing a Python `Pipfile`.
 
diff --git a/snyk/models.py b/snyk/models.py
index 43c69f1..238e6ce 100644
--- a/snyk/models.py
+++ b/snyk/models.py
@@ -164,7 +164,7 @@ def notification_settings(self):
     def invite(self, email: str, admin: bool = False):
         raise SnykNotImplementedError  # pragma: no cover
 
-    def _test(self, path, contents=None):
+    def _test(self, path, contents=None, additional=None):
         if contents:
             # Check for a file-like object, allows us to support files
             # and strings in the same interface
@@ -176,6 +176,15 @@ def _test(self, path, contents=None):
                 "encoding": "base64",
                 "files": {"target": {"contents": encoded}},
             }
+
+            # Some test methods carry a second file, often a lock file
+            if additional:
+                read = getattr(additional, "read", None)
+                if callable(read):
+                    additional = additional.read()
+                encoded = base64.b64encode(additional.encode()).decode()
+                post_body["files"]["additional"] = {"contents": encoded}
+
             resp = self.client.post(path, post_body)
         else:
             resp = self.client.get(path)
@@ -212,9 +221,9 @@ def test_gemfilelock(self, contents):
         path = "test/rubygems?org=%s" % self.id
         return self._test(path, contents)
 
-    def test_packagejson(self, contents):
+    def test_packagejson(self, contents, lock=None):
         path = "test/npm?org=%s" % self.id
-        return self._test(path, contents)
+        return self._test(path, contents, lock)
 
     def test_gradlefile(self, contents):
         path = "test/gradle?org=%s" % self.id
@@ -228,6 +237,14 @@ def test_pom(self, contents):
         path = "test/maven?org=%s" % self.id
         return self._test(path, contents)
 
+    def test_composer(self, contents, lock):
+        path = "test/composer?org=%s" % self.id
+        return self._test(path, contents, lock)
+
+    def test_yarn(self, contents, lock):
+        path = "test/yarn?org=%s" % self.id
+        return self._test(path, contents, lock)
+
 
 @dataclass
 class Integration(DataClassJSONMixin):
diff --git a/snyk/test_models.py b/snyk/test_models.py
index d0bfc2a..c70b2b3 100644
--- a/snyk/test_models.py
+++ b/snyk/test_models.py
@@ -139,6 +139,13 @@ def test_packagejson_test_with_file(
         requests_mock.post("%s/test/npm" % base_url, json=blank_test)
         assert organization.test_packagejson(fake_file)
 
+    def test_packagejson_test_with_files(
+        self, organization, base_url, blank_test, fake_file, requests_mock
+    ):
+
+        requests_mock.post("%s/test/npm" % base_url, json=blank_test)
+        assert organization.test_packagejson(fake_file, fake_file)
+
     def test_gradlefile_test_with_file(
         self, organization, base_url, blank_test, fake_file, requests_mock
     ):
@@ -160,6 +167,20 @@ def test_pom_test_with_file(
         requests_mock.post("%s/test/maven" % base_url, json=blank_test)
         assert organization.test_pom(fake_file)
 
+    def test_composer_with_files(
+        self, organization, base_url, blank_test, fake_file, requests_mock
+    ):
+
+        requests_mock.post("%s/test/composer" % base_url, json=blank_test)
+        assert organization.test_composer(fake_file, fake_file)
+
+    def test_yarn_with_files(
+        self, organization, base_url, blank_test, fake_file, requests_mock
+    ):
+
+        requests_mock.post("%s/test/yarn" % base_url, json=blank_test)
+        assert organization.test_yarn(fake_file, fake_file)
+
     def test_missing_package_test(self, organization, base_url, requests_mock):
         requests_mock.get("%s/test/rubygems/puppet/4.0.0" % base_url, status_code=404)
         with pytest.raises(SnykError):