select previous: should be from last selected not pivot #14

Author: codingedgar

package.json

@@ -1,6 +1,6 @@
 {
   "name": "macos-multi-select",
-  "version": "0.1.4",
+  "version": "0.1.5",
   "description": "Given a list of ids, and an action, return a list of selected items with the same behaviour of macOS finder list view selection.",
   "main": "dist/index.js",
   "repository": "[email protected]:codingedgar/macos-multi-select.git",

src/index.ts

@@ -82,6 +82,7 @@ export function multiselect(context: Context, command: Command): Context {
     return {
       ...context,
       selected: take(n, context.list),
+      adjacentPivot: head(context.list),
     }
   } else if (
     command.type === "SELECT ADJACENT" &&
@@ -160,9 +161,9 @@ export function multiselect(context: Context, command: Command): Context {
   } else if (
     command.type === "SELECT PREVIOUS" &&
     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 > 0) {
       const prevItem = context.list[pivotIndex - 1];

src/spec/selectPrevious.spec.ts

@@ -110,4 +110,63 @@ describe('Select Previous Item', () => {
     )
   })
 
+  test('Should select previous 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 > 0 ? currentSelectionPivot - 1 : 0
+          const nextPivot = list[nextSelection];
+
+          expect(
+            multiselect(
+              prevContext,
+              {
+                type: "SELECT PREVIOUS",
+              }
+            )
+          )
+          .toEqual({
+            list,
+            selected: [nextPivot],
+            adjacentPivot: nextPivot,
+          })
+
+        }
+      )
+    )
+  })
+
 });