Range Based Numeric Check

src/Microsoft.Extensions.HealthChecks/Checks/NumericChecks.cs

@@ -65,5 +65,36 @@ public static HealthCheckBuilder AddMaxValueCheck<T>(this HealthCheckBuilder bui
 
             return builder;
         }
+
+        public static HealthCheckBuilder AddRangeValueCheck<T>(this HealthCheckBuilder builder, string name, (T minValue, T maxValue) range, Func<T> currentValueFunc) where T : IComparable<T>
+        {
+            Guard.ArgumentNotNull(nameof(builder), builder);
+
+            return AddRangeValueCheck(builder, name, range, currentValueFunc, builder.DefaultCacheDuration);
+        }
+
+        public static HealthCheckBuilder AddRangeValueCheck<T>(this HealthCheckBuilder builder, string name, (T minValue,T maxValue) range, Func<T> currentValueFunc, TimeSpan cacheDuration)
+            where T : IComparable<T>
+        {
+            Guard.ArgumentNotNull(nameof(builder), builder);
+            Guard.ArgumentNotNullOrEmpty(nameof(name), name);
+            Guard.ArgumentNotNull(nameof(currentValueFunc), currentValueFunc);
+
+            builder.AddCheck(name, () =>
+            {
+                var currentValue = currentValueFunc();
+                var status = currentValue.CompareTo(range.maxValue) <= 0 && currentValue.CompareTo(range.minValue) >= 0 ? CheckStatus.Healthy : CheckStatus.Unhealthy;
+                return HealthCheckResult.FromStatus(
+                    status,
+                    $"min={range.minValue},max={range.maxValue}, current={currentValue}",
+                    new Dictionary<string, object> { { "max", range.maxValue }, { "min", range.minValue }, { "current", currentValue } }
+                );
+            }, cacheDuration);
+
+
+            return builder;
+        }
+
+
     }
 }

src/Microsoft.Extensions.HealthChecks/Microsoft.Extensions.HealthChecks.csproj

@@ -2,6 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard1.3</TargetFramework>
+    <LangVersion>7.2</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>
@@ -15,6 +16,7 @@
     <PackageReference Include="System.Threading.Tasks.Parallel" Version="4.3.0" />
     <PackageReference Include="System.Threading.Thread" Version="4.3.0" />
     <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.3.0" />
+    <PackageReference Include="System.ValueTuple" Version="4.5.0" />
   </ItemGroup>
 
 </Project>

test/Microsoft.Extensions.HealthChecks.Test/Checks/NumericChecksTest.cs

@@ -88,5 +88,51 @@ public async void RegistersCheck(int monitoredValue, CheckStatus expectedStatus)
                 );
             }
         }
+
+        public class AddRangeValueCheck : NumericChecksTest
+        {
+            [Fact]
+            public void GuardClauses()
+            {
+                Assert.Throws<ArgumentNullException>("builder", () => HealthCheckBuilderExtensions.AddRangeValueCheck(null, "name",(0,40), () => 2112));
+                Assert.Throws<ArgumentNullException>("name", () => HealthCheckBuilderExtensions.AddRangeValueCheck(_builder, null, (0, 40), () => 2112));
+                Assert.Throws<ArgumentException>("name", () => HealthCheckBuilderExtensions.AddRangeValueCheck(_builder, "", (0, 40), () => 2112));
+                Assert.Throws<ArgumentNullException>("currentValueFunc", () => HealthCheckBuilderExtensions.AddRangeValueCheck(_builder, "name", (0, 40), null));
+            }
+
+            [Theory]
+            [InlineData(11, CheckStatus.Unhealthy)]
+            [InlineData(6, CheckStatus.Healthy)]
+            public async void RegistersCheck(int monitoredValue, CheckStatus expectedStatus)
+            {
+                var minValue = 5;
+                var maxValue = 10;
+
+                _builder.AddRangeValueCheck("CheckName", (minValue: minValue,maxValue:maxValue), () => monitoredValue);
+
+                var check = _builder.ChecksByName["CheckName"];
+
+                var result = await check.RunAsync(_serviceProvider);
+                Assert.Equal(expectedStatus, result.CheckStatus);
+                Assert.Equal($"min={minValue},max={maxValue}, current={monitoredValue}", result.Description);
+                Assert.Collection(result.Data.OrderBy(kvp => kvp.Key),
+                    kvp =>
+                    {
+                        Assert.Equal("current", kvp.Key);
+                        Assert.Equal(monitoredValue, kvp.Value);
+                    },
+                    kvp =>
+                    {
+                        Assert.Equal("max", kvp.Key);
+                        Assert.Equal(maxValue, kvp.Value);
+                    },
+                    kvp =>
+                    {
+                        Assert.Equal("min", kvp.Key);
+                        Assert.Equal(minValue, kvp.Value);
+                    }
+                );
+            }
+        }
     }
 }

test/Microsoft.Extensions.HealthChecks.Test/Microsoft.Extensions.HealthChecks.Test.csproj

@@ -5,6 +5,10 @@
     <RootNamespace>Microsoft.Extensions.HealthChecks</RootNamespace>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="System.ValueTuple" Version="4.5.0" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\..\src\Microsoft.Extensions.HealthChecks\Microsoft.Extensions.HealthChecks.csproj" />
   </ItemGroup>