use options param, update docs, update tests

docs/USING_PRO.md

@@ -82,12 +82,12 @@ slugger.slug('foo-1') // foo-1-2
 ...
 ```
 
-`slugger` also has a stateless method `slugText` which does not update the internal accumulator:
+`slugger.slug` can also be called with the `dryrun` option for stateless operation:
 ```js
 slugger.slug('foo')                    // foo
-slugger.slugText('foo')  // foo-1
+slugger.slug('foo', { dryrun: true })  // foo-1
 slugger.slug('foo')                    // foo-1
-slugger.slugText('foo')  // foo-2
+slugger.slug('foo', { dryrun: true })  // foo-2
 slugger.slug('foo')                    // foo-2
 ...
 ```

src/Slugger.js

@@ -39,17 +39,11 @@ module.exports = class Slugger {
 
   /**
    * Convert string to unique id
+   * @param {object} options
+   * @param {boolean} options.dryrun Generates the next unique slug without updating the internal accumulator.
    */
-  slug(value) {
+  slug(value, options = {}) {
     const slug = this.serialize(value);
-    return this.getNextSafeSlug(slug);
-  }
-
-  /**
-   * Get slug text without incrementing accumulator
-   */
-  slugText(value) {
-    const slug = this.serialize(value);
-    return this.getNextSafeSlug(slug, true);
+    return this.getNextSafeSlug(slug, options.dryrun);
   }
 };

test/unit/marked-spec.js

@@ -64,11 +64,17 @@ describe('Test slugger functionality', () => {
     expect(slugger.slug('<em>html</em>')).toBe('html');
   });
 
-  it('should not increment seen when just getting text', () => {
+  it('should not increment seen when using dryrun option', () => {
     const slugger = new marked.Slugger();
-    slugger.slugText('<h1>This Section</h1>');
+    slugger.slug('<h1>This Section</h1>', { dryrun: true });
     expect(slugger.slug('<h1>This Section</h1>')).toBe('this-section');
   });
+
+  it('should still return the next unique id when using dryrun', () => {
+    const slugger = new marked.Slugger();
+    expect(slugger.slug('<h1>This Section</h1>')).toBe('this-section');
+    expect(slugger.slug('<h1>This Section</h1>', { dryrun: true })).toBe('this-section-1');
+  });
 });
 
 describe('Test paragraph token type', () => {