SIA-R65: Provide classes and number of matches in diagnostic

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

@@ -0,0 +1,67 @@
+import { Diagnostic } from "@siteimprove/alfa-act";
+import { Map } from "@siteimprove/alfa-map";
+
+export type Matches = {
+  matchingTargets: number;
+  matchingNonTargets: number;
+};
+
+/**
+ * @internal
+ */
+export class ExtendedDiagnostic extends Diagnostic {
+  public static of(
+    message: string,
+    matches: Map<string, Matches> = Map.empty()
+  ): Diagnostic {
+    return new ExtendedDiagnostic(message, matches);
+  }
+
+  private readonly _matches: Map<string, Matches>;
+
+  private constructor(message: string, matches: Map<string, Matches>) {
+    super(message);
+    this._matches = matches;
+  }
+
+  public equals(value: ExtendedDiagnostic): boolean;
+
+  public equals(value: unknown): value is this;
+
+  public equals(value: unknown): boolean {
+    return (
+      value instanceof ExtendedDiagnostic &&
+      value._matches.equals(this._matches)
+    );
+  }
+
+  public toJSON(): ExtendedDiagnostic.JSON {
+    return {
+      ...super.toJSON(),
+      matches: this._matches.toJSON(),
+    };
+  }
+}
+
+/**
+ * @internal
+ */
+export namespace ExtendedDiagnostic {
+  export interface JSON extends Diagnostic.JSON {
+    matches: Map.JSON<string, Matches>;
+  }
+
+  export function isExtendedDiagnostic(
+    value: Diagnostic
+  ): value is ExtendedDiagnostic;
+
+  export function isExtendedDiagnostic(
+    value: unknown
+  ): value is ExtendedDiagnostic;
+
+  export function isExtendedDiagnostic(
+    value: unknown
+  ): value is ExtendedDiagnostic {
+    return value instanceof ExtendedDiagnostic;
+  }
+}