diff --git a/tests/test_bec_monitor.py b/tests/test_bec_monitor.py
index 32235006..7c6f258b 100644
--- a/tests/test_bec_monitor.py
+++ b/tests/test_bec_monitor.py
@@ -42,6 +42,39 @@ config_device = {
 }
 
 
+config_device_no_entry = {
+    "plot_settings": {
+        "background_color": "white",
+        "num_columns": 5,  # Number of columns higher than the actual number of plots
+        "colormap": "plasma",
+        "scan_types": False,
+    },
+    "plot_data": [
+        {
+            "plot_name": "BPM4i plots vs samx",
+            "x": {
+                "label": "Motor Y",
+                "signals": [{"name": "samx"}],  # Entry is missing
+            },
+            "y": {
+                "label": "bpm4i",
+                "signals": [{"name": "bpm4i"}],  # Entry is missing
+            },
+        },
+        {
+            "plot_name": "Gauss plots vs samx",
+            "x": {
+                "label": "Motor X",
+                "signals": [{"name": "samx"}],  # Entry is missing
+            },
+            "y": {
+                "label": "Gauss",
+                "signals": [{"name": "gauss_bpm"}],  # Entry is missing
+            },
+        },
+    ],
+}
+
 config_scan = {
     "plot_settings": {
         "background_color": "white",
@@ -58,7 +91,6 @@ config_scan = {
                     "label": "BPM",
                     "signals": [
                         {"name": "gauss_bpm", "entry": "gauss_bpm"},
-                        {"name": "gauss_adc1", "entry": "gauss_adc1"},
                     ],
                 },
             },
@@ -68,7 +100,6 @@ config_scan = {
                 "y": {
                     "label": "BPM",
                     "signals": [
-                        {"name": "gauss_bpm", "entry": "gauss_bpm"},
                         {"name": "gauss_adc1", "entry": "gauss_adc1"},
                     ],
                 },
@@ -78,7 +109,7 @@ config_scan = {
                 "x": {"label": "Motor Y", "signals": [{"name": "samx", "entry": "samx"}]},
                 "y": {
                     "label": "BPM",
-                    "signals": [{"name": "gauss_bpm", "entry": "gauss_bpm"}],
+                    "signals": [{"name": "gauss_adc2", "entry": "gauss_adc2"}],
                 },
             },
             {
@@ -86,7 +117,7 @@ config_scan = {
                 "x": {"label": "Motor Y", "signals": [{"name": "samx", "entry": "samx"}]},
                 "y": {
                     "label": "BPM",
-                    "signals": [{"name": "gauss_adc3", "entry": "gauss_adc3"}],
+                    "signals": [{"name": "bpm4i", "entry": "bpm4i"}],
                 },
             },
         ],
@@ -109,7 +140,6 @@ config_scan = {
                 "y": {
                     "label": "Multi",
                     "signals": [
-                        {"name": "gauss_bpm", "entry": "gauss_bpm"},
                         {"name": "bpm4i", "entry": "bpm4i"},
                     ],
                 },
@@ -128,7 +158,7 @@ def setup_monitor(qtbot, config):
     return widget
 
 
-@pytest.fixture(scope="module")
+@pytest.fixture(scope="module")  # TODO is this needed?
 def app():
     app = QApplication([])
     yield app
@@ -145,7 +175,12 @@ def qtbot(app, qtbot):  # TODO is this needed?
 
 
 @pytest.mark.parametrize(
-    "config, scan_type, number_of_plots", [(config_device, False, 2), (config_scan, True, 4)]
+    "config, scan_type, number_of_plots",
+    [
+        (config_device, False, 2),
+        (config_scan, True, 4),
+        (config_device_no_entry, False, 2),
+    ],
 )
 def test_initialization_with_device_config(qtbot, config, scan_type, number_of_plots):
     widget = setup_monitor(qtbot, config)
@@ -189,9 +224,104 @@ def test_render_initial_plots(
 
     # Validate number of columns
     assert widget.plot_settings["num_columns"] == expected_num_columns
+
     # Validate the plots are created correctly
     for expected_name in expected_plot_names:
         assert expected_name in widget.plots.keys()
 
     # Validate the grid_coordinates
     assert widget.grid_coordinates == expected_coordinates
+
+
+def mock_getitem(dev_name):
+    """Helper function to mock the __getitem__ method of the 'dev'."""
+    mock_instance = MagicMock()
+    if dev_name == "samx":
+        mock_instance._hints = "samx"
+    elif dev_name == "bpm4i":
+        mock_instance._hints = "bpm4i"
+    elif dev_name == "gauss_bpm":
+        mock_instance._hints = "gauss_bpm"
+
+    return mock_instance
+
+
+# mocked messages and metadatas
+msg_1 = {
+    "data": {
+        "samx": {"samx": {"value": 10}},
+        "bpm4i": {"bpm4i": {"value": 5}},
+        "gauss_bpm": {"gauss_bpm": {"value": 6}},
+        "gauss_adc1": {"gauss_adc1": {"value": 8}},
+        "gauss_adc2": {"gauss_adc2": {"value": 9}},
+    },
+    "scanID": 1,
+}
+metadata_grid = {"scan_name": "grid_scan"}
+metadata_line = {"scan_name": "line_scan"}
+
+
+@pytest.mark.parametrize(
+    "config, msg, metadata, expected_data",
+    [
+        # case: msg does not have 'scanid'
+        (config_device, {"data": {}}, {}, {}),
+        # case: scan_types is false, msg contains all valid fields, and entry is present in config
+        (
+            config_device,
+            msg_1,
+            {},
+            {
+                ("samx", "samx", "bpm4i", "bpm4i"): {"x": [10], "y": [5]},
+                ("samx", "samx", "gauss_adc1", "gauss_adc1"): {"x": [10], "y": [8]},
+                ("samx", "samx", "gauss_adc2", "gauss_adc2"): {"x": [10], "y": [9]},
+            },
+        ),
+        # case: scan_types is false, msg contains all valid fields and entry is missing in config, should use hints
+        (
+            config_device_no_entry,
+            msg_1,
+            {},
+            {
+                ("samx", "samx", "bpm4i", "bpm4i"): {"x": [10], "y": [5]},
+                ("samx", "samx", "gauss_bpm", "gauss_bpm"): {"x": [10], "y": [6]},
+            },
+        ),
+        # case: scan_types is true, msg contains all valid fields, metadata contains scan "line_scan:"
+        (
+            config_scan,
+            msg_1,
+            metadata_line,
+            {
+                ("samx", "samx", "bpm4i", "bpm4i"): {"x": [10], "y": [5]},
+                ("samx", "samx", "gauss_bpm", "gauss_bpm"): {"x": [10], "y": [6]},
+                ("samx", "samx", "gauss_adc1", "gauss_adc1"): {"x": [10], "y": [8]},
+                ("samx", "samx", "gauss_adc2", "gauss_adc2"): {"x": [10], "y": [9]},
+            },
+        ),
+        (
+            config_scan,
+            msg_1,
+            metadata_grid,
+            {
+                ("samx", "samx", "bpm4i", "bpm4i"): {"x": [10], "y": [5]},
+                ("samx", "samx", "gauss_adc1", "gauss_adc1"): {"x": [10], "y": [8]},
+                ("samx", "samx", "gauss_adc2", "gauss_adc2"): {"x": [10], "y": [9]},
+                ("samx", "samx", "gauss_bpm", "gauss_bpm"): {"x": [10], "y": [6]},
+            },
+        ),
+    ],
+)
+def test_on_scan_segment(qtbot, config, msg, metadata, expected_data):
+    plot_app = setup_monitor(qtbot, config)
+
+    # Initialize and run test
+    # plot_app.init_curves = MagicMock()
+    plot_app.data = {}
+    plot_app.scanID = 0
+
+    # Get hints
+    plot_app.dev.__getitem__.side_effect = mock_getitem
+
+    plot_app.on_scan_segment(msg, metadata)
+    assert plot_app.data == expected_data
diff --git a/tests/test_configs/config_device.yaml b/tests/test_configs/config_device.yaml
new file mode 100644
index 00000000..1298bdbc
--- /dev/null
+++ b/tests/test_configs/config_device.yaml
@@ -0,0 +1,30 @@
+plot_settings:
+  background_color: "black"
+  num_columns: 1
+  colormap: "plasma"
+  scan_types: false
+plot_data:
+- plot_name: "BPM4i plots vs samx"
+  x:
+    label: "Motor Y"
+    signals:
+    - name: "samx"
+      entry: "samx"
+  y:
+    label: "bpm4i"
+    signals:
+    - name: "bpm4i"
+      entry: "bpm4i"
+- plot_name: "Gauss plots vs samx"
+  x:
+    label: "Motor X"
+    signals:
+    - name: "samx"
+      entry: "samx"
+  y:
+    label: "Gauss"
+    signals:
+    - name: "gauss_adc1"
+      entry: "gauss_adc1"
+    - name: "gauss_adc2"
+      entry: "gauss_adc2"
diff --git a/tests/test_configs/config_device_no_entry.yaml b/tests/test_configs/config_device_no_entry.yaml
new file mode 100644
index 00000000..a73a9ae4
--- /dev/null
+++ b/tests/test_configs/config_device_no_entry.yaml
@@ -0,0 +1,24 @@
+plot_settings:
+  background_color: "white"
+  num_columns: 5
+  colormap: "plasma"
+  scan_types: false
+plot_data:
+- plot_name: "BPM4i plots vs samx"
+  x:
+    label: "Motor Y"
+    signals:
+    - name: "samx"
+  y:
+    label: "bpm4i"
+    signals:
+    - name: "bpm4i"
+- plot_name: "Gauss plots vs samx"
+  x:
+    label: "Motor X"
+    signals:
+    - name: "samx"
+  y:
+    label: "Gauss"
+    signals:
+    - name: "gauss_bpm"
diff --git a/tests/test_configs/config_scan.yaml b/tests/test_configs/config_scan.yaml
new file mode 100644
index 00000000..cf0d1950
--- /dev/null
+++ b/tests/test_configs/config_scan.yaml
@@ -0,0 +1,77 @@
+plot_settings:
+  background_color: "white"
+  num_columns: 3
+  colormap: "plasma"
+  scan_types: true
+plot_data:
+  grid_scan:
+  - plot_name: "Grid plot 1"
+    x:
+      label: "Motor X"
+      signals:
+      - name: "samx"
+        entry: "samx"
+    y:
+      label: "BPM"
+      signals:
+      - name: "gauss_bpm"
+        entry: "gauss_bpm"
+  - plot_name: "Grid plot 2"
+    x:
+      label: "Motor X"
+      signals:
+      - name: "samx"
+        entry: "samx"
+    y:
+      label: "BPM"
+      signals:
+      - name: "gauss_adc1"
+        entry: "gauss_adc1"
+  - plot_name: "Grid plot 3"
+    x:
+      label: "Motor Y"
+      signals:
+      - name: "samx"
+        entry: "samx"
+    y:
+      label: "BPM"
+      signals:
+      - name: "gauss_adc2"
+        entry: "gauss_adc2"
+  - plot_name: "Grid plot 4"
+    x:
+      label: "Motor Y"
+      signals:
+      - name: "samx"
+        entry: "samx"
+    y:
+      label: "BPM"
+      signals:
+      - name: "bpm4i"
+        entry: "bpm4i"
+  line_scan:
+  - plot_name: "Multiple Gauss Plot"
+    x:
+      label: "Motor X"
+      signals:
+      - name: "samx"
+    y:
+      label: "BPM"
+      signals:
+      - name: "gauss_bpm"
+        entry: "gauss_bpm"
+      - name: "gauss_adc1"
+        entry: "gauss_adc1"
+      - name: "gauss_adc2"
+        entry: "gauss_adc2"
+  - plot_name: "BPM Plot"
+    x:
+      label: "Motor X"
+      signals:
+      - name: "samx"
+        entry: "samx"
+    y:
+      label: "Multi"
+      signals:
+      - name: "bpm4i"
+        entry: "bpm4i"