test(json-crdt-extensions): 💍 add .refVisible() test

Author: streamich

src/json-crdt-extensions/peritext/point/Point.ts

@@ -237,6 +237,12 @@ export class Point implements Pick<Stateful, 'refresh'>, Printable {
     return;
   }
 
+  /**
+   * Returns one character to the left of the point, or `undefined` if there
+   * is no such character. Skips any deleted characters. Handles absolute points.
+   *
+   * @returns A character slice to the left of the point.
+   */
   public leftChar(): ChunkSlice | undefined {
     const str = this.txt.str;
     if (this.isAbsEnd()) {
@@ -253,6 +259,12 @@ export class Point implements Pick<Stateful, 'refresh'>, Printable {
     return new ChunkSlice(chunk, off, 1);
   }
 
+  /**
+   * Returns one character to the right of the point, or `undefined` if there
+   * is no such character. Skips any deleted characters. Handles absolute points.
+   *
+   * @returns A character slice to the right of the point.
+   */
   public rightChar(): ChunkSlice | undefined {
     const str = this.txt.str;
     if (this.isAbsStart()) {
@@ -321,16 +333,6 @@ export class Point implements Pick<Stateful, 'refresh'>, Printable {
     return !!id && equal(this.id, id);
   }
 
-  /**
-   * Modifies the location of the point, such that the spatial location remains
-   * and anchor remains the same, but ensures that the point references a
-   * visible (non-deleted) character.
-   */
-  public refVisible(): void {
-    if (this.anchor === Anchor.Before) this.refBefore();
-    else this.refAfter();
-  }
-
   /**
    * Sets the point to the absolute start of the string.
    */
@@ -415,6 +417,16 @@ export class Point implements Pick<Stateful, 'refresh'>, Printable {
     this.id = this.prevId() || this.txt.str.id;
   }
 
+  /**
+   * Modifies the location of the point, such that the spatial location remains
+   * the same and tries to preserve anchor location, but ensures that the point
+   * references a visible (not deleted) character.
+   */
+  public refVisible(): void {
+    if (this.anchor === Anchor.Before) this.refBefore();
+    else this.refAfter();
+  }
+
   /**
    * Moves point past given number of visible characters. Accepts positive
    * and negative distances.

src/json-crdt-extensions/peritext/point/__tests__/Point.spec.ts

@@ -1019,6 +1019,34 @@ describe('.refAfter()', () => {
   });
 });
 
+
+describe('.refVisible()', () => {
+  test('skips deleted chars, attaches to visible char', () => {
+    const {peritext} = setupWithChunkedText();
+    peritext.strApi().del(0, peritext.str.length());
+    peritext.strApi().ins(0, '123456789');
+    const mid1 = peritext.pointAt(4, Anchor.After);
+    const mid2 = peritext.pointAt(5, Anchor.Before);
+    expect(mid1.leftChar()!.view()).toBe('5');
+    expect(mid1.rightChar()!.view()).toBe('6');
+    expect(mid2.leftChar()!.view()).toBe('5');
+    expect(mid2.rightChar()!.view()).toBe('6');
+    const left = peritext.pointAt(2, Anchor.After);
+    expect(left.leftChar()!.view()).toBe('3');
+    const right = peritext.pointAt(6, Anchor.Before);
+    expect(right.rightChar()!.view()).toBe('7');
+    peritext.strApi().del(3, 3);
+    expect(left.leftChar()!.view()).toBe('3');
+    expect(right.rightChar()!.view()).toBe('7');
+    expect(mid1.compare(left) > 0).toBe(true);
+    mid1.refVisible();
+    expect(mid1.compare(left) === 0).toBe(true);
+    expect(mid2.compare(right) < 0).toBe(true);
+    mid2.refVisible();
+    expect(mid2.compare(right) === 0).toBe(true);
+  });
+});
+
 describe('.move()', () => {
   test('smoke test', () => {
     const {peritext} = setupWithChunkedText();