New: Don't retest connections, indexers, download clients, etc if re-saved with the exact same settings

(cherry picked from commit 71fd09f162b2880c461e03cba4317c34ee3203dc)
(cherry picked from commit 804a5921b3b620e2407d5d6a7fd69fb1fd9b0cbf)
(cherry picked from commit 65cb1ccafd54479fa3fca1f1eaa4b96222b0176b)

src/NzbDrone.Core/ThingiProvider/ProviderDefinition.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Text.Json.Serialization;
 using NzbDrone.Core.Datastore;
 
 namespace NzbDrone.Core.ThingiProvider
@@ -13,7 +14,10 @@ namespace NzbDrone.Core.ThingiProvider
         private IProviderConfig _settings;
 
         public string Name { get; set; }
+
+        [JsonIgnore]
         public string ImplementationName { get; set; }
+
         public string Implementation { get; set; }
         public string ConfigContract { get; set; }
         public virtual bool Enable { get; set; }

src/Prowlarr.Api.V1/ProviderControllerBase.cs

@@ -3,6 +3,7 @@ using System.Linq;
 using FluentValidation;
 using FluentValidation.Results;
 using Microsoft.AspNetCore.Mvc;
+using NzbDrone.Common.Serializer;
 using NzbDrone.Core.ThingiProvider;
 using NzbDrone.Core.Validation;
 using NzbDrone.Http.REST.Attributes;
@@ -69,7 +70,7 @@ namespace Prowlarr.Api.V1
         [Produces("application/json")]
         public ActionResult<TProviderResource> CreateProvider([FromBody] TProviderResource providerResource, [FromQuery] bool forceSave = false)
         {
-            var providerDefinition = GetDefinition(providerResource, true, !forceSave, false);
+            var providerDefinition = GetDefinition(providerResource, null, true, !forceSave, false);
 
             if (providerDefinition.Enable)
             {
@@ -86,15 +87,24 @@ namespace Prowlarr.Api.V1
         [Produces("application/json")]
         public ActionResult<TProviderResource> UpdateProvider([FromBody] TProviderResource providerResource, [FromQuery] bool forceSave = false)
         {
-            var providerDefinition = GetDefinition(providerResource, true, !forceSave, false);
+            var existingDefinition = _providerFactory.Find(providerResource.Id);
+            var providerDefinition = GetDefinition(providerResource, existingDefinition, true, !forceSave, false);
 
-            // Only test existing definitions if it is enabled and forceSave isn't set.
-            if (providerDefinition.Enable && !forceSave)
+            // Comparing via JSON string to eliminate the need for every provider implementation to implement equality checks.
+            // Compare settings separately because they are not serialized with the definition.
+            var hasDefinitionChanged = STJson.ToJson(existingDefinition) != STJson.ToJson(providerDefinition) ||
+                                       STJson.ToJson(existingDefinition.Settings) != STJson.ToJson(providerDefinition.Settings);
+
+            // Only test existing definitions if it is enabled and forceSave isn't set and the definition has changed.
+            if (providerDefinition.Enable && !forceSave && hasDefinitionChanged)
             {
                 Test(providerDefinition, true);
             }
 
-            _providerFactory.Update(providerDefinition);
+            if (hasDefinitionChanged)
+            {
+                _providerFactory.Update(providerDefinition);
+            }
 
             return Accepted(providerResource.Id);
         }
@@ -140,9 +150,8 @@ namespace Prowlarr.Api.V1
             return Accepted(_providerFactory.Update(definitionsToUpdate).Select(x => _resourceMapper.ToResource(x)));
         }
 
-        private TProviderDefinition GetDefinition(TProviderResource providerResource, bool validate, bool includeWarnings, bool forceValidate)
+        private TProviderDefinition GetDefinition(TProviderResource providerResource, TProviderDefinition existingDefinition, bool validate, bool includeWarnings, bool forceValidate)
         {
-            var existingDefinition = providerResource.Id > 0 ? _providerFactory.Find(providerResource.Id) : null;
             var definition = _resourceMapper.ToModel(providerResource, existingDefinition);
 
             if (validate && (definition.Enable || forceValidate))
@@ -199,7 +208,8 @@ namespace Prowlarr.Api.V1
         [Consumes("application/json")]
         public object Test([FromBody] TProviderResource providerResource)
         {
-            var providerDefinition = GetDefinition(providerResource, true, true, true);
+            var existingDefinition = providerResource.Id > 0 ? _providerFactory.Find(providerResource.Id) : null;
+            var providerDefinition = GetDefinition(providerResource, existingDefinition, true, true, true);
 
             Test(providerDefinition, true);
 
@@ -232,9 +242,10 @@ namespace Prowlarr.Api.V1
         [HttpPost("action/{name}")]
         [Consumes("application/json")]
         [Produces("application/json")]
-        public IActionResult RequestAction(string name, [FromBody] TProviderResource resource)
+        public IActionResult RequestAction(string name, [FromBody] TProviderResource providerResource)
         {
-            var providerDefinition = GetDefinition(resource, false, false, false);
+            var existingDefinition = providerResource.Id > 0 ? _providerFactory.Find(providerResource.Id) : null;
+            var providerDefinition = GetDefinition(providerResource, existingDefinition, false, false, false);
 
             var query = Request.Query.ToDictionary(x => x.Key, x => x.Value.ToString());