Add PreferDataLoader to suggest using DataLoader where possible

Author: SinZ163

src/SMAPI.ModBuildConfig.Analyzer.Tests/ContentManagerAnalyzerTests.cs

@@ -92,14 +92,46 @@ public void BadType_RaisesDiagnostic(string codeText, int column, string assetNa
                 Id = "AvoidContentManagerBadType",
                 Message = $"'{assetName}' uses the {suggestedType} type, but {expectedType} is in use instead. See https://smapi.io/package/avoid-contentmanager-type for details.",
                 Severity = DiagnosticSeverity.Error,
-                Locations = new[] { new DiagnosticResultLocation("Test0.cs", SampleCodeLine, SampleCodeColumn + column) }
+                Locations = [new DiagnosticResultLocation("Test0.cs", SampleCodeLine, SampleCodeColumn + column)]
+            };
+            DiagnosticResult preferDataLoader = new()
+            {
+                Id = "PreferContentManagerDataLoader",
+                Message = $"'{assetName[5..]}' can be accessed using 'DataLoader.{assetName[5..]}(LocalizedContentManager content)' instead. See https://smapi.io/package/prefer-contentmanager-dataloader for details.",
+                Severity = DiagnosticSeverity.Info,
+                Locations = [new DiagnosticResultLocation("Test0.cs", SampleCodeLine, SampleCodeColumn + column)]
+            };
+
+            // assert
+            this.VerifyCSharpDiagnostic(code, expected, preferDataLoader);
+        }
+
+
+
+        /// <summary>Test that the expected diagnostic message is raised for avoidable net field references.</summary>
+        /// <param name="codeText">The code line to test.</param>
+        /// <param name="column">The column within the code line where the diagnostic message should be reported.</param>
+        /// <param name="expression">The expression which should be reported.</param>
+        /// <param name="netType">The net type name which should be reported.</param>
+        /// <param name="suggestedProperty">The suggested property name which should be reported.</param>
+        [TestCase("Game1.content.Load<Dictionary<string, string>>(\"Data\\\\Fish\");", 0, "Fish")]
+        public void PreferDataLoader_RaisesDiagnostic(string codeText, int column, string assetName)
+        {
+            // arrange
+            string code = SampleProgram.Replace("{{test-code}}", codeText);
+            DiagnosticResult preferDataLoader = new()
+            {
+                Id = "PreferContentManagerDataLoader",
+                Message = $"'{assetName}' can be accessed using 'DataLoader.{assetName}(LocalizedContentManager content)' instead. See https://smapi.io/package/prefer-contentmanager-dataloader for details.",
+                Severity = DiagnosticSeverity.Info,
+                Locations = [new DiagnosticResultLocation("Test0.cs", SampleCodeLine, SampleCodeColumn + column)]
             };
 
             // assert
-            this.VerifyCSharpDiagnostic(code, expected);
+            this.VerifyCSharpDiagnostic(code, preferDataLoader);
         }
 
-        [TestCase("Game1.content.Load<Dictionary<string, string>>(\"Data\\\\Fish\");", true)]
+        [TestCase("Game1.content.Load<Dictionary<string, string>>(\"Data\\\\Custom_Asset\");", true)]
         [TestCase(SampleUnrelatedGoodProgram, false)]
 
         public void ValidCode_HasNoDiagnostics(string codeText, bool useWrapper)

src/SMAPI.ModBuildConfig.Analyzer.Tests/SMAPI.ModBuildConfig.Analyzer.Tests.csproj

@@ -15,5 +15,9 @@
     <ProjectReference Include="..\SMAPI.ModBuildConfig.Analyzer\SMAPI.ModBuildConfig.Analyzer.csproj" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Folder Include="Mock\StardewModdingAPI\" />
+  </ItemGroup>
+
   <Import Project="..\..\build\common.targets" />
 </Project>

src/SMAPI.ModBuildConfig.Analyzer/ContentManagerAnalyzer.cs

@@ -16,7 +16,7 @@ public class ContentManagerAnalyzer : DiagnosticAnalyzer
         public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; }
 
 
-        /// <summary>The diagnostic info for an avoidable net field access.</summary>
+        /// <summary>The diagnostic info for an avoidable runtime casting error.</summary>
         private readonly DiagnosticDescriptor AvoidBadTypeRule = new(
             id: "AvoidContentManagerBadType",
             title: "Avoid incorrectly typing ContentManager Loads",
@@ -26,10 +26,20 @@ public class ContentManagerAnalyzer : DiagnosticAnalyzer
             isEnabledByDefault: true,
             helpLinkUri: "https://smapi.io/package/avoid-contentmanager-type"
         );
+        /// <summary>The diagnostic info for best practices using DataLoader</summary>
+        private readonly DiagnosticDescriptor PreferDataLoader = new(
+            id: "PreferContentManagerDataLoader",
+            title: "Prefer using DataLoader to ContentManager Loads",
+            messageFormat: "'{0}' can be accessed using 'DataLoader.{0}(LocalizedContentManager content)' instead. See https://smapi.io/package/prefer-contentmanager-dataloader for details.",
+            category: "SMAPI.CommonErrors",
+            defaultSeverity: DiagnosticSeverity.Info,
+            isEnabledByDefault: true,
+            helpLinkUri: "https://smapi.io/package/prefer-contentmanager-dataloader"
+        );
 
         public ContentManagerAnalyzer()
         {
-            this.SupportedDiagnostics = ImmutableArray.CreateRange(new[] { this.AvoidBadTypeRule });
+            this.SupportedDiagnostics = ImmutableArray.CreateRange(new[] { this.AvoidBadTypeRule, this.PreferDataLoader });
         }
 
         public override void Initialize(AnalysisContext context)
@@ -69,6 +79,7 @@ private void AnalyzeContentManagerLoads(SyntaxNodeAnalysisContext context)
                 {
                     context.ReportDiagnostic(Diagnostic.Create(this.AvoidBadTypeRule, context.Node.GetLocation(), assetName, method.ReturnType.ToString(), genericArgument.ToString()));
                 }
+                context.ReportDiagnostic(Diagnostic.Create(this.PreferDataLoader, context.Node.GetLocation(), dataAsset));
             }
         }
     }