Add oidcIssuers getter to Agent (#28)

Co-authored-by: Samu Lang <langsamu@users.noreply.github.com>

Author: jeswr

src/webid/Agent.ts

@@ -63,6 +63,10 @@ export class Agent extends TermWrapper {
         return SetFrom.subjectPredicate(this, SOLID.storage, NamedNodeAs.string, NamedNodeFrom.string)
     }
 
+    get oidcIssuer(): Set<string> {
+        return SetFrom.subjectPredicate(this, SOLID.oidcIssuer, NamedNodeAs.string, NamedNodeFrom.string)
+    }
+
     get email(): string | null {
         return this.hasEmail?.value ?? null
     }

test/unit/agent.test.ts

@@ -0,0 +1,33 @@
+import { DataFactory, Parser, Store } from "n3"
+import assert from "node:assert"
+import { describe, it } from "node:test"
+
+import { Agent } from "@solid/object"
+
+describe("Agent oidcIssuer", () => {
+
+    const sampleRDF = `
+@prefix solid: <http://www.w3.org/ns/solid/terms#> .
+@prefix foaf: <http://xmlns.com/foaf/0.1/> .
+
+<https://example.org/profile/card#me>
+    a foaf:Person ;
+    solid:oidcIssuer <https://idp.example.org/> , <https://idp.other.example/> .
+`;
+
+    it("returns the set of solid:oidcIssuer values declared on the WebID", () => {
+        const store = new Store()
+        store.addQuads(new Parser().parse(sampleRDF))
+
+        const agent = new Agent(
+            DataFactory.namedNode("https://example.org/profile/card#me"),
+            store,
+            DataFactory
+        )
+
+        assert.deepStrictEqual(
+            new Set(agent.oidcIssuer),
+            new Set(["https://idp.example.org/", "https://idp.other.example/"])
+        )
+    })
+})