handle edge case: all null PrecursorIntensity falls back to Score for normalization

When every filtered result has null PrecursorIntensity in PrecursorIntensity
mode, fall back to Score to derive a meaningful min/max/range instead of
showing '0 - 0' on the gradient bar. Adds test coverage for this path.

Author: nbollis

MetaMorpheus/GuiFunctions/MetaDraw/BioPolymerCoverage/BioPolymerCoverageMapViewModel.cs

@@ -297,6 +297,8 @@ private void Redraw()
                         ? r.Match.PrecursorIntensity ?? double.NaN
                         : r.Match.Score)
                     .Where(v => !double.IsNaN(v)).ToList();
+                if (vals.Count == 0 && _colorBy == ColorResultsBy.PrecursorIntensity)
+                    vals = filteredResults.Select(r => r.Match.Score).ToList();
                 if (vals.Count > 0) { minVal = vals.Min(); maxVal = vals.Max(); }
                 range = maxVal - minVal;
                 if (range < double.Epsilon) range = 1;

MetaMorpheus/Test/MetaDraw/BioPolymerCoverageMapViewModelTests.cs

@@ -474,9 +474,12 @@ public void Plotting_WithPrecursorIntensity_SomeNull_DoesNotCrash()
         vm.ColorBy = ColorResultsBy.PrecursorIntensity;
 
         var matchWithIntensity = new DummySpectralmatch();
+        matchWithIntensity.SetScore(200);
         var matchNullIntensity = new DummySpectralmatch();
+        matchNullIntensity.SetScore(100);
         var backingField = typeof(SpectrumMatchFromTsv)
             .GetField("<PrecursorIntensity>k__BackingField", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
+        backingField.SetValue(matchWithIntensity, 500000.0);
         backingField.SetValue(matchNullIntensity, null);
 
         var result1 = new BioPolymerCoverageResultModel(matchWithIntensity, "ABC", 1, 2, BioPolymerCoverageType.Unique);
@@ -488,5 +491,29 @@ public void Plotting_WithPrecursorIntensity_SomeNull_DoesNotCrash()
         Assert.That(vm.CoverageDrawing, Is.Not.Null);
     }
 
+    [Test]
+    public void Plotting_WithPrecursorIntensity_AllNull_FallsBackToScore()
+    {
+        var vm = new BioPolymerCoverageMapViewModel();
+        vm.ColorBy = ColorResultsBy.PrecursorIntensity;
+
+        var match1 = new DummySpectralmatch();
+        match1.SetScore(10);
+        var match2 = new DummySpectralmatch();
+        match2.SetScore(1000);
+        var backingField = typeof(SpectrumMatchFromTsv)
+            .GetField("<PrecursorIntensity>k__BackingField", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
+        backingField.SetValue(match1, null);
+        backingField.SetValue(match2, null);
+
+        var result1 = new BioPolymerCoverageResultModel(match1, "ABC", 1, 2, BioPolymerCoverageType.Unique);
+        var result2 = new BioPolymerCoverageResultModel(match2, "ABC", 2, 3, BioPolymerCoverageType.Unique);
+
+        var group = new BioPolymerGroupViewModel("ACC", "Prot", "ABC", new[] { result1, result2 });
+        vm.Group = group;
+
+        Assert.That(vm.CoverageDrawing, Is.Not.Null);
+    }
+
     #endregion
 }