CDD-2220: Update alt text for simplified chart when there is no trend

metrics/domain/models/plots_text.py

@@ -347,6 +347,8 @@ def _get_trend_direction(cls, *, plot_parameters: PlotParameters) -> str:
                 return "positive"
             case RGBAChartLineColours.TREND_LINE_NEUTRAL.name:
                 return "neutral"
+            case _:
+                return "none"
 
     def _describe_plot_type(self, *, plot_parameters: PlotParameters) -> str:
         line_type: str = self._get_line_type_or_default(plot_parameters=plot_parameters)
@@ -357,7 +359,12 @@ def _describe_plot_type(self, *, plot_parameters: PlotParameters) -> str:
 
         if self._plot_is_simplified_chart(plot_parameters=plot_parameters):
             trend_type: str = self._get_trend_direction(plot_parameters=plot_parameters)
-            return f"This is a {line_type} {plot_type} chart, showing a {trend_type} trend in the data. "
+            plot_description = f"This is a {line_type} {plot_type} chart, "
+
+            if trend_type != "none":
+                plot_description += f"showing a {trend_type} trend in the data. "
+
+            return plot_description
 
         return f"This is a {line_colour} {line_type} {plot_type} plot. "
 

tests/unit/metrics/domain/models/test_plots_text.py

@@ -150,6 +150,27 @@ def test_returns_correct_trend_type_when_line_colour_provided_is_for_trend_line(
         )
         assert expected_text_about_parameters in text
 
+    def test_returns_no_trend_type_when_line_colour_is_trend_line_none(
+        self,
+        fake_plot_data: PlotData,
+    ):
+        """
+        Given a valid plot where the `line_colour` that is not a `TREND_LINE` colour
+        When the `construct_text()` method is called
+        Then no trend type is returned in the response.
+        """
+        fake_plot_data.parameters.line_colour = "COLOUR_1_DARK_BLUE"
+        fake_plot_data.parameters.line_type = "SOLID"
+        fake_plot_data.parameters.chart_type = ChartTypes.line_single_simplified.value
+        plots_text = PlotsText(plots_data=[fake_plot_data])
+
+        # When
+        text: str = plots_text.construct_text()
+
+        # Then
+        expected_text_about_parameters = f"This is a solid line chart,"
+        assert expected_text_about_parameters in text
+
     def test_returns_correct_text_about_parameters_for_multiple_plots(
         self, fake_plot_data: PlotData
     ):