Added id to storystore

lib/core/src/client/preview/id.js

@@ -0,0 +1,29 @@
+// NOTE: this file is common to both `lib/ui` (manager) and `lib/core` (preview).
+// For now it is reproduced in both places (ick) rather than create a new package.
+// We should figure out what we are doing here.
+
+// Create a id/slug compatible string from an arbitrary string. We:
+//   1. replace all non-alphanumerics with '-', and downcase.
+//   2. replace all runs of '-' with a single '-',
+//        except if they are at the end, in which case, replace them with ''
+
+function sanitize(string) {
+  return string
+    .toLowerCase()
+    .replace(/[^a-z0-9-]/g, '-')
+    .replace(/-+/g, '-')
+    .replace(/^-+/, '')
+    .replace(/-+$/, '');
+}
+
+function sanitizeSafe(string, part) {
+  const sanitized = sanitize(string);
+  if (sanitized === '') {
+    throw new Error(`Invalid ${part} '${string}', must include alphanumeric characters`);
+  }
+  return sanitized;
+}
+
+export default function toId(kind, story) {
+  return `${sanitizeSafe(kind, 'kind')}--${sanitizeSafe(story, 'story')}`;
+}

lib/core/src/client/preview/id.test.js

@@ -0,0 +1,38 @@
+import toId from './id';
+
+describe('toId', () => {
+  [
+    // name, kind, story, output
+    ['handles simple cases', 'kind', 'story', 'kind--story'],
+    ['handles basic substitution', 'a b$c?d😀e', '1-2:3', 'a-b-c-d-e--1-2-3'],
+    ['handles runs of non-url chars', 'a?&*b', 'story', 'a-b--story'],
+    ['removes non-url chars from start and end', '?ab-', 'story', 'ab--story'],
+    ['downcases', 'KIND', 'STORY', 'kind--story'],
+  ].forEach(([name, kind, story, output]) => {
+    it(name, () => {
+      expect(toId(kind, story)).toBe(output);
+    });
+  });
+
+  it('does not allow kind with *no* url chars', () => {
+    expect(() => toId('?', 'asdf')).toThrow(
+      `Invalid kind '?', must include alphanumeric characters`
+    );
+  });
+
+  it('does not allow empty kind', () => {
+    expect(() => toId('', 'asdf')).toThrow(`Invalid kind '', must include alphanumeric characters`);
+  });
+
+  it('does not allow story with *no* url chars', () => {
+    expect(() => toId('kind', '?')).toThrow(
+      `Invalid story '?', must include alphanumeric characters`
+    );
+  });
+
+  it('does not allow empty story', () => {
+    expect(() => toId('kind', '')).toThrow(
+      `Invalid story '', must include alphanumeric characters`
+    );
+  });
+});