SIA-R65: Provide classes and number of matches in diagnostic (#1164)

* SIA-ER65: Split result to show why we pass

* Simplify reason

* Updated PR according to review comments

* Removed ER65, moved extended diagnostics to R65 and introduced number of matches

* Updated nonTargets to exclude targets

* Seperated matchingTargets and matchingNonTargets

* Ran yarn document

* Polish code

* Cleanup

* Fix up test

docs/review/api/alfa-rules.api.md

@@ -368,6 +368,10 @@ export namespace Diagnostic {
     //
     // (undocumented)
     isDistinguishingStylesDeprecated: typeof DistinguishingStyles_2.isDistinguishingStyles;
+    const // Warning: (ae-forgotten-export) The symbol "MatchingClasses" needs to be exported by the entry point index.d.ts
+    //
+    // (undocumented)
+    isMatchingClasses: typeof MatchingClasses.isMatchingClasses;
     const // Warning: (ae-forgotten-export) The symbol "LabelAndName" needs to be exported by the entry point index.d.ts
     //
     // (undocumented)

packages/alfa-rules/src/common/act/diagnostic.ts

@@ -3,6 +3,7 @@ import { Languages } from "../../sia-r109/rule";
 import { LabelAndName } from "../../sia-r14/rule";
 import { RoleAndRequiredAttributes } from "../../sia-r16/rule";
 import { SameNames } from "../../sia-r56/rule";
+import { MatchingClasses } from "../../sia-r65/diagnostics";
 import { DistinguishingStyles as DeprecatedDistinguishingStyles } from "../../sia-dr62/rule";
 import { DeprecatedElements } from "../../sia-r70/rule";
 import { WithDeclaration } from "../../sia-r75/rule";
@@ -37,6 +38,8 @@ export namespace Diagnostic {
   export const { isDistinguishingStyles: isDistinguishingStylesDeprecated } =
     DeprecatedDistinguishingStyles;
 
+  export const { isMatchingClasses } = MatchingClasses;
+
   export const { isLabelAndName } = LabelAndName;
 
   export const { isLanguages } = Languages;

packages/alfa-rules/src/sia-r65/diagnostics.ts

@@ -0,0 +1,73 @@
+import { Diagnostic } from "@siteimprove/alfa-act";
+import { Map } from "@siteimprove/alfa-map";
+
+export class MatchingClasses extends Diagnostic {
+  public static of(
+    message: string,
+    matchingTargets: Map<string, number> = Map.empty(),
+    matchingNonTargets: Map<string, number> = Map.empty()
+  ): Diagnostic {
+    return new MatchingClasses(message, matchingTargets, matchingNonTargets);
+  }
+
+  private readonly _matchingTargets: Map<string, number>;
+  private readonly _matchingNonTargets: Map<string, number>;
+
+  private constructor(
+    message: string,
+    matchingTargets: Map<string, number>,
+    matchingNonTargets: Map<string, number>
+  ) {
+    super(message);
+    this._matchingTargets = matchingTargets;
+    this._matchingNonTargets = matchingNonTargets;
+  }
+
+  public get matchingTargets(): Map<string, number> {
+    return this._matchingTargets;
+  }
+
+  public get matchingNonTargets(): Map<string, number> {
+    return this._matchingNonTargets;
+  }
+
+  public equals(value: MatchingClasses): boolean;
+
+  public equals(value: unknown): value is this;
+
+  public equals(value: unknown): boolean {
+    return (
+      value instanceof MatchingClasses &&
+      value._matchingTargets.equals(this._matchingTargets) &&
+      value._matchingNonTargets.equals(this._matchingNonTargets)
+    );
+  }
+
+  public toJSON(): MatchingClasses.JSON {
+    return {
+      ...super.toJSON(),
+      matchingTargets: this._matchingTargets.toJSON(),
+      matchingNonTargets: this._matchingNonTargets.toJSON(),
+    };
+  }
+}
+
+/**
+ * @internal
+ */
+export namespace MatchingClasses {
+  export interface JSON extends Diagnostic.JSON {
+    matchingTargets: Map.JSON<string, number>;
+    matchingNonTargets: Map.JSON<string, number>;
+  }
+
+  export function isMatchingClasses(
+    value: Diagnostic
+  ): value is MatchingClasses;
+
+  export function isMatchingClasses(value: unknown): value is MatchingClasses;
+
+  export function isMatchingClasses(value: unknown): value is MatchingClasses {
+    return value instanceof MatchingClasses;
+  }
+}