diff --git a/test/conftest.py b/test/conftest.py
index cd59e43a..6d7950d0 100644
--- a/test/conftest.py
+++ b/test/conftest.py
@@ -51,6 +51,36 @@ def single_investigation_test_data(icat_client):
     icat_client.delete(investigation)
 
 
+@pytest.fixture()
+def multiple_investigation_test_data(icat_client):
+    investigation_test_data = []
+    investigation_dicts = []
+    meta_attributes = Entity.MetaAttr
+
+    for i in range(5):
+        investigation = icat_client.new("investigation")
+        investigation.name = f"Test Data for DataGateway API Testing {i}"
+        investigation.title = (
+            f"Test data for the Python ICAT Backend on DataGateway API {i}"
+        )
+        investigation.visitId = str(uuid.uuid1())
+        investigation.facility = icat_client.get("Facility", 1)
+        investigation.type = icat_client.get("InvestigationType", 1)
+        investigation.create()
+        investigation_test_data.append(investigation)
+        investigation_dict = investigation.as_dict()
+
+        for attr in meta_attributes:
+            investigation_dict.pop(attr)
+
+        investigation_dicts.append(investigation_dict)
+
+    yield investigation_dicts
+
+    for entity in investigation_test_data:
+        icat_client.delete(entity)
+
+
 @pytest.fixture()
 def flask_test_app():
     app.config["TESTING"] = True
diff --git a/test/icat/test_standard_endpoints.py b/test/icat/test_standard_endpoints.py
index a48d177d..5a76945d 100644
--- a/test/icat/test_standard_endpoints.py
+++ b/test/icat/test_standard_endpoints.py
@@ -44,6 +44,26 @@ def test_valid_get_with_filters(
 
         assert response_json == single_investigation_test_data
 
+    @pytest.mark.usefixtures("multiple_investigation_test_data")
+    def test_valid_get_with_filters_distinct(
+        self, flask_test_app, valid_credentials_header,
+    ):
+        test_response = flask_test_app.get(
+            '/investigations?where={"title": {"like": "Test data for the Python ICAT'
+            ' Backend on DataGateway API"}}&distinct="title"',
+            headers=valid_credentials_header,
+        )
+
+        expected = [
+            {
+                "title": f"Test data for the Python ICAT Backend on DataGateway API {i}"
+                for i in range(5)
+            },
+        ]
+
+        for title in expected:
+            assert title in test_response.json
+
     def test_invalid_get_with_filters(self):
         # Invalid data?
         pass
@@ -113,10 +133,21 @@ def test_valid_get_with_id(
 
         assert response_json == single_investigation_test_data
 
-    def test_invalid_get_with_id(self):
+    def test_invalid_get_with_id(self, flask_test_app, valid_credentials_header):
         # Do a get one with filters (order desc), extract the id of that, add 5 and do a
         # request for that
-        pass
+        # Need to identify the ID given to the test data
+        final_investigation_result = flask_test_app.get(
+            '/investigations/findone?order="id DESC"', headers=valid_credentials_header,
+        )
+        test_data_id = final_investigation_result.json["id"]
+
+        # Adding 100 onto the ID to the most recent result should ensure a 404
+        test_response = flask_test_app.get(
+            f"/investigations/{test_data_id + 100}", headers=valid_credentials_header,
+        )
+
+        assert test_response.status_code == 404
 
     def test_valid_delete_with_id(self):
         pass