Added tests for the new public methods in UnitSystem

- updated the comments and invalid arguments checks
- added a few tests for those cases

a few question marks remain (marked with TODOs)

Author: lipchev

UnitsNet.Tests/UnitSystemTests.cs

@@ -2,6 +2,7 @@
 // Copyright 2013 Andreas Gullberg Larsen ([email protected]). Maintained at https://github.com/angularsen/UnitsNet.
 
 using System;
+using System.Linq;
 using UnitsNet.Units;
 using Xunit;
 
@@ -149,5 +150,55 @@ public void SIUnitSystemHasCorrectBaseUnits()
             Assert.Equal(AmountOfSubstanceUnit.Mole, UnitSystem.SI.BaseUnits.Amount);
             Assert.Equal(LuminousIntensityUnit.Candela, UnitSystem.SI.BaseUnits.LuminousIntensity);
         }
+
+        [Fact]
+        public void GetDefaultUnitInfoThrowsExceptionForUndefinedQuantity()
+        {
+            Assert.Throws<ArgumentException>(() => UnitSystem.SI.GetDefaultUnitInfo(QuantityType.Undefined));
+        }
+
+        [Fact]
+        public void GetDefaultUnitInfoReturnsNullForQuantitiesWithNoDefaultUnits()
+        {
+            // TODO do we expect to preserve this behavior?
+            // AmplitudeRatio might be unitless- but there are (more than one) ways to express ratios. 
+            Assert.Null(UnitSystem.SI.GetDefaultUnitInfo(AmplitudeRatio.QuantityType));
+        }
+
+        [Fact]
+        public void WithDefaultUnitThrowsIfQuantityTypeIsUndefined()
+        {
+            Assert.Throws<ArgumentException>(() => UnitSystem.SI.WithDefaultUnit(QuantityType.Undefined, null));
+        }
+
+        [Fact]
+        public void WithDefaultUnitUsesOldBaseUnitsIfNotSpecified()
+        {
+            var myDefaultLengthUnit = Length.Info.UnitInfos.First(x => x.Value == LengthUnit.Millimeter);
+
+            var newSI = UnitSystem.SI.WithDefaultUnit(QuantityType.Length, myDefaultLengthUnit, (BaseUnits) null); 
+
+            Assert.Equal(UnitSystem.SI, newSI); // currently comparing using BaseUnits
+        }
+
+        [Theory]
+        [InlineData(LengthUnit.Undefined, MassUnit.Kilogram, DurationUnit.Second, ElectricCurrentUnit.Ampere, TemperatureUnit.Kelvin, AmountOfSubstanceUnit.Mole, LuminousIntensityUnit.Candela)]
+        [InlineData(LengthUnit.Meter, MassUnit.Undefined, DurationUnit.Second, ElectricCurrentUnit.Ampere, TemperatureUnit.Kelvin, AmountOfSubstanceUnit.Mole, LuminousIntensityUnit.Candela)]
+        [InlineData(LengthUnit.Meter, MassUnit.Kilogram, DurationUnit.Undefined, ElectricCurrentUnit.Ampere, TemperatureUnit.Kelvin, AmountOfSubstanceUnit.Mole, LuminousIntensityUnit.Candela)]
+        [InlineData(LengthUnit.Meter, MassUnit.Kilogram, DurationUnit.Second, ElectricCurrentUnit.Undefined, TemperatureUnit.Kelvin, AmountOfSubstanceUnit.Mole, LuminousIntensityUnit.Candela)]
+        [InlineData(LengthUnit.Meter, MassUnit.Kilogram, DurationUnit.Second, ElectricCurrentUnit.Ampere, TemperatureUnit.Undefined, AmountOfSubstanceUnit.Mole, LuminousIntensityUnit.Candela)]
+        [InlineData(LengthUnit.Meter, MassUnit.Kilogram, DurationUnit.Second, ElectricCurrentUnit.Ampere, TemperatureUnit.Kelvin, AmountOfSubstanceUnit.Undefined, LuminousIntensityUnit.Candela)]
+        [InlineData(LengthUnit.Meter, MassUnit.Kilogram, DurationUnit.Second, ElectricCurrentUnit.Ampere, TemperatureUnit.Kelvin, AmountOfSubstanceUnit.Mole, LuminousIntensityUnit.Undefined)]
+        public void WithDefaultUnitThrowsIfSpecifiedBaseUnitsNotFullyDefined(LengthUnit length, MassUnit mass, DurationUnit time, ElectricCurrentUnit current,
+            TemperatureUnit temperature, AmountOfSubstanceUnit amount, LuminousIntensityUnit luminousIntensity)
+        {
+            var myDefaultLengthUnit = Length.Info.UnitInfos.First(x => x.Value == LengthUnit.Millimeter);
+
+            var baseUnits = new BaseUnits(length, mass, time, current, temperature, amount, luminousIntensity);
+
+            // TODO do we want to preserve this behavior?
+            Assert.Throws<ArgumentException>(()=> UnitSystem.SI.WithDefaultUnit(QuantityType.Length, myDefaultLengthUnit, baseUnits));
+        }
+
     }
 }

UnitsNet/UnitSystem.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using JetBrains.Annotations;
 using UnitsNet.Units;
 
 namespace UnitsNet
@@ -125,11 +126,13 @@ public override int GetHashCode()
         ///     The default UnitInfo for the given quantity type, if such an association exists,
         ///     and <see langword="null" /> otherwise.
         /// </returns>
-        /// <exception cref="T:System.Collections.Generic.KeyNotFoundException">
-        ///     The given <paramref name="quantityType" /> is not available in this unit system.
+        /// <exception cref="ArgumentException">
+        ///     Quantity type can not be undefined.
         /// </exception>
         public UnitInfo GetDefaultUnitInfo(QuantityType quantityType)
         {
+            if (quantityType == QuantityType.Undefined)
+                throw new ArgumentException("Quantity type can not be undefined.", nameof(quantityType));
             return _defaultUnits.Value[(int)quantityType - 1];
         }
 
@@ -145,11 +148,15 @@ public UnitInfo GetDefaultUnitInfo(QuantityType quantityType)
         ///     A new UnitSystem that defines <paramref name="defaultUnitInfo" /> as the default unit for
         ///     <paramref name="quantityType" />
         /// </returns>
-        /// <exception cref="T:System.ArgumentNullException">
-        ///     <paramref name="quantityType" /> is <see langword="null" />.
+        /// <exception cref="ArgumentException">
+        ///     Quantity type can not be undefined.
         /// </exception>
         public UnitSystem WithDefaultUnit(QuantityType quantityType, UnitInfo defaultUnitInfo, BaseUnits baseUnits = null)
         {
+            if (quantityType == QuantityType.Undefined)
+                throw new ArgumentException("Quantity type can not be undefined.", nameof(quantityType));
+
+            // TODO any way to check if UnitInfo is of QuantityType?
             var newBaseUnits = baseUnits ?? BaseUnits;
 
             var newDefaultUnits = _defaultUnits.Value.ToArray();