AreaDensity: Add g/m2, mg/m2, add operators (#1134)

* Added g/m2 and mg/m2 to AreaDensity. fix #1131

* #1131 Removed wrong operator for AreaDensity

* Rename test case

* Added and moved unit tests for AreaDensity and Mass operators

Co-authored-by: Andreas Gullberg Larsen <[email protected]>

Author: Brunni

Common/UnitDefinitions/AreaDensity.json

@@ -1,7 +1,7 @@
 {
   "Name": "AreaDensity",
   "BaseUnit": "KilogramPerSquareMeter",
-  "XmlDoc": "The area density of a two-dimensional object is calculated as the mass per unit area.",
+  "XmlDoc": "The area density of a two-dimensional object is calculated as the mass per unit area. For paper this is also called grammage.",
   "BaseDimensions": {
     "L": -2,
     "M": 1
@@ -22,6 +22,40 @@
           "Abbreviations": [ "kg/m²" ]
         }
       ]
+    },
+    {
+      "SingularName": "GramPerSquareMeter",
+      "PluralName": "GramsPerSquareMeter",
+      "BaseUnits": {
+        "L": "Meter",
+        "M": "Gram"
+      },
+      "FromUnitToBaseFunc": "{x} / 1000",
+      "FromBaseToUnitFunc": "{x} * 1000",
+      "XmlDocSummary": "Also known as grammage for paper industry. In fiber industry used with abbreviation 'gsm'.",
+      "XmlDocRemarks": "https://en.wikipedia.org/wiki/Grammage",
+      "Localization": [
+        {
+          "Culture": "en-US",
+          "Abbreviations": [ "g/m²", "gsm" ]
+        }
+      ]
+    },
+    {
+      "SingularName": "MilligramPerSquareMeter",
+      "PluralName": "MilligramsPerSquareMeter",
+      "BaseUnits": {
+        "L": "Meter",
+        "M": "Milligram"
+      },
+      "FromUnitToBaseFunc": "{x} / 1000000",
+      "FromBaseToUnitFunc": "{x} * 1000000",
+      "Localization": [
+        {
+          "Culture": "en-US",
+          "Abbreviations": [ "mg/m²" ]
+        }
+      ]
     }
   ]
 }

Common/UnitEnumValues.g.json

@@ -93,7 +93,9 @@
     "UsSurveySquareFoot": 14
   },
   "AreaDensity": {
-    "KilogramPerSquareMeter": 1
+    "KilogramPerSquareMeter": 1,
+    "GramPerSquareMeter": 6,
+    "MilligramPerSquareMeter": 10
   },
   "AreaMomentOfInertia": {
     "CentimeterToTheFourth": 1,

UnitsNet.NanoFramework/GeneratedCode/Quantities/AreaDensity.g.cs

@@ -22,13 +22,25 @@
 
 
 using System;
+using Xunit;
 
 namespace UnitsNet.Tests.CustomCode
 {
     public class AreaDensityTests : AreaDensityTestsBase
     {
         protected override bool SupportsSIUnitSystem => true;
 
+        protected override double GramsPerSquareMeterInOneKilogramPerSquareMeter => 1000;
+
         protected override double KilogramsPerSquareMeterInOneKilogramPerSquareMeter => 1;
+
+        protected override double MilligramsPerSquareMeterInOneKilogramPerSquareMeter => 1000000;
+
+        [Fact]
+        public void AreaDensityTimesAreaEqualsMass()
+        {
+            Mass massOfOneA4Paper = AreaDensity.FromGramsPerSquareMeter(120) * Area.FromSquareCentimeters(625);
+            Assert.Equal(Mass.FromGrams(7.5), massOfOneA4Paper);
+        }
     }
 }

UnitsNet.NanoFramework/GeneratedCode/Units/AreaDensityUnit.g.cs

@@ -93,6 +93,20 @@ public void MassDividedByVolumeEqualsDensity()
             Assert.Equal(density, Density.FromKilogramsPerCubicMeter(6));
         }
 
+        [Fact]
+        public void MassDividedByAreaEqualsAreaDensity()
+        {
+            AreaDensity grammage = Mass.FromKilograms(0.9) / Area.FromSquareMeters(3);
+            Assert.Equal(AreaDensity.FromKilogramsPerSquareMeter(0.3), grammage);
+        }
+
+        [Fact]
+        public void MassDividedByAreaDensityEqualsArea()
+        {
+            Area area = Mass.FromKilograms(10) / AreaDensity.FromKilogramsPerSquareMeter(5);
+            Assert.Equal(Area.FromSquareMeters(2), area);
+        }
+
         [Fact]
         public void MassTimesAccelerationEqualsForce()
         {