serializer: fix: prefix generation breaks when starting with 'a'

src/serializer.js

@@ -170,7 +170,7 @@ export class Serializer {
     if (slash >= 0) p = p.slice(slash + 1)
     var i = 0
     while (i < p.length) {
-      if (this.prefixchars.indexOf(p[i])) {
+      if (this.prefixchars.indexOf(p[i]) >= 0) {
         i++
       } else {
         break

tests/unit/serializer-test.ts

@@ -0,0 +1,53 @@
+import { expect } from "chai";
+import { graph, Serializer } from "../../src/index";
+
+describe("Serializer", () => {
+	describe("can make up prefixes", () => {
+		const serializer = Serializer(graph());
+		afterEach(() => {
+			serializer.prefixes = [];
+			serializer.namespaces = [];
+		});
+
+		it("with a simple URI", () => {
+			const prefix = serializer.makeUpPrefix("http://example.org");
+			expect(prefix).to.equal("exa");
+		});
+
+		it("with a URI with a trailing slash", () => {
+			const prefix = serializer.makeUpPrefix("http://example.org/");
+			expect(prefix).to.equal("exa");
+		});
+
+		it("with a URI ending with a #", () => {
+			const prefix = serializer.makeUpPrefix("http://example.org#");
+			expect(prefix).to.equal("exa");
+		});
+
+		it("with a URI with multiple slashes", () => {
+			const prefix = serializer.makeUpPrefix(
+				"http://www.w3.org/ns/shacl"
+			);
+			expect(prefix).to.equal("shacl");
+		});
+
+		it("with a URI with multiple slashes and a #", () => {
+			const prefix = serializer.makeUpPrefix(
+				"http://www.w3.org/ns/shacl#"
+			);
+			expect(prefix).to.equal("shacl");
+		});
+
+		it("with a URI with multiple slashes and a #/", () => {
+			const prefix = serializer.makeUpPrefix(
+				"http://www.w3.org/ns/shacl#/"
+			);
+			expect(prefix).to.equal("shacl");
+		});
+
+		it("with a URI starting with 'a'", () => {
+			const prefix = serializer.makeUpPrefix("http://aschema.org");
+			expect(prefix).to.equal("asc");
+		});
+	});
+});