select next: should be from last selected not pivot #15

Author: codingedgar

src/arrayUtils.ts

@@ -32,7 +32,8 @@ export function findNextPivot(
 export function findAdjacentToPivotInSortedArray(
   sortedArray: string[],
   subarray: string[],
-  item: string): string[] {
+  item: string
+): string[] {
     const indexOfItem = sortedArray.indexOf(item);
     let leftIndex = indexOfItem;
     let rightIndex = indexOfItem;

src/index.ts

@@ -123,12 +123,13 @@ export function multiselect(context: Context, command: Command): Context {
   } else if (
     command.type === "SELECT NEXT" &&
     context.list.length &&
-    context.adjacentPivot !== undefined
+    context.selected.length
     ) {
-    const pivotIndex = context.list.indexOf(context.adjacentPivot)
+    const pivotIndex = context.list.indexOf(last(context.selected)!)
 
     if (pivotIndex < context.list.length - 1) {
       const nextItem = context.list[pivotIndex + 1];
+
       return {
         ...context,
         selected: [nextItem],
@@ -137,12 +138,14 @@ export function multiselect(context: Context, command: Command): Context {
     } else if (
       !(
         context.selected.length === 1 &&
-        last(context.selected) === last(context.list)
+        context.selected[0] === last(context.list)
       )
     ) {
+      const pivot = context.list[pivotIndex];
       return {
         ...context,
-        selected: [context.list[pivotIndex]],
+        selected: [pivot],
+        adjacentPivot: pivot,
       }
     } else {
       return context;

src/spec/selectNext.spec.ts

@@ -103,4 +103,66 @@ describe('Select Next Item', () => {
     )
   });
 
+  test('Should select next from the last selected (not the pivot) given the last command were select adjacent', () => {
+    fc.assert(
+      fc.property(
+        fc.tuple(
+          fc.boolean(),
+          fc.set(
+            fc.string(), { minLength: 1 }
+            )
+        )
+        .chain(([undefOrTop, list]) =>
+          fc.nat(list.length - 1)
+          .map(id => ({
+            list,
+            adjacentPivot: undefOrTop ? undefined : head(list),
+            id: list[id],
+          }))
+        )
+        ,
+        ({
+          adjacentPivot,
+          list,
+          id,
+        }) => {
+
+          const prevContext = multiselect(
+            {
+              list,
+              adjacentPivot: adjacentPivot,
+              selected: []
+            },
+            {
+              type: "SELECT ADJACENT",
+              id,
+            }
+          )
+
+          const currentSelectionPivot = list.indexOf(id)
+          const nextSelection = currentSelectionPivot < list.length - 1
+            ? currentSelectionPivot + 1
+            : list.length - 1;
+
+          const nextPivot = list[nextSelection];
+
+          expect(
+            multiselect(
+              prevContext,
+              {
+                type: "SELECT NEXT",
+              }
+            )
+          )
+          .toEqual({
+            list,
+            selected: [nextPivot],
+            adjacentPivot: nextPivot,
+          })
+
+        }
+      )
+    )
+  })
+
 })