#69 : Add unit tests

src/components/Carousel/Carousel.svelte

@@ -14,7 +14,7 @@
   } from '../../utils/event'
   import {
     applyParticleSizes,
-    getCurrentPageIndex,
+    getCurrentPageIndexByCurrentParticleIndex,
     getPartialPageSize,
     getPagesCountByParticlesCount,
     getParticleIndexByPageIndex,
@@ -157,10 +157,11 @@
   })
 
   let currentParticleIndex = 0
-  $: currentPageIndex = getCurrentPageIndex({
+  $: currentPageIndex = getCurrentPageIndexByCurrentParticleIndex({
     currentParticleIndex,
     particlesCount,
-    headClonesCount: clonesCount.head,
+    clonesCountHead: clonesCount.head,
+    clonesCountTotal: clonesCount.total,
     infinite,
     particlesToScroll,
   })
@@ -232,8 +233,8 @@
       clonesToAppend,
       clonesToPrepend,
     } = getClones({
-      headClonesCount: clonesCount.head,
-      tailClonesCount: clonesCount.tail,
+      clonesCountHead: clonesCount.head,
+      clonesCountTail: clonesCount.tail,
       particlesContainerChildren: particlesContainer.children,
     })
     applyClones({

src/utils/clones.js

@@ -1,17 +1,17 @@
 export function getClones({
-  headClonesCount,
-  tailClonesCount,
+  clonesCountHead,
+  clonesCountTail,
   particlesContainerChildren,
 }) {
   // TODO: add fns to remove clones if needed
   const clonesToAppend = []
-  for (let i=0; i<tailClonesCount; i++) {
+  for (let i=0; i<clonesCountTail; i++) {
     clonesToAppend.push(particlesContainerChildren[i].cloneNode(true))
   }
 
   const clonesToPrepend = []
   const len = particlesContainerChildren.length
-  for (let i=len-1; i>len-1-headClonesCount; i--) {
+  for (let i=len-1; i>len-1-clonesCountHead; i--) {
     clonesToPrepend.push(particlesContainerChildren[i].cloneNode(true))
   }
 

src/utils/page.js

@@ -12,19 +12,50 @@ export function applyParticleSizes({
   }
 }
 
-export function getCurrentPageIndex({
+// getCurrentPageIndexByCurrentParticleIndex
+
+export function _getCurrentPageIndexByCurrentParticleIndexInfinite({
   currentParticleIndex,
   particlesCount,
-  headClonesCount,
+  clonesCountHead,
+  clonesCountTotal,
+  particlesToScroll,
+}) {
+  if (currentParticleIndex === particlesCount - clonesCountHead) return 0
+  if (currentParticleIndex === 0) return _getPagesCountByParticlesCountInfinite({
+    particlesCountWithoutClones: particlesCount - clonesCountTotal,
+    particlesToScroll,
+  }) - 1
+  return Math.floor((currentParticleIndex - clonesCountHead) / particlesToScroll)
+}
+
+export function _getCurrentPageIndexByCurrentParticleIndexLimited({
+  currentParticleIndex,
+  particlesToScroll,
+}) {
+  return Math.ceil(currentParticleIndex / particlesToScroll)
+}
+
+export function getCurrentPageIndexByCurrentParticleIndex({
+  currentParticleIndex,
+  particlesCount,
+  clonesCountHead,
+  clonesCountTotal,
   infinite,
   particlesToScroll,
 }) {
-  if (infinite) {
-    if (currentParticleIndex === particlesCount - headClonesCount) return 0
-    if (currentParticleIndex === 0) return particlesCount - headClonesCount
-    return Math.floor((currentParticleIndex - headClonesCount) / particlesToScroll)
-  }
-  return Math.ceil(currentParticleIndex / particlesToScroll)
+  return infinite
+    ? _getCurrentPageIndexByCurrentParticleIndexInfinite({
+      currentParticleIndex,
+      particlesCount,
+      clonesCountHead,
+      clonesCountTotal,
+      particlesToScroll,
+    })
+    : _getCurrentPageIndexByCurrentParticleIndexLimited({
+      currentParticleIndex,
+      particlesToScroll,
+    })
 }
 
 // TODO: think about case if particlesCount < particlesToShow and particlesCount < particlesToScroll
@@ -45,17 +76,41 @@ export function getPartialPageSize({
   }
 }
 
+// getPagesCountByParticlesCount
+
+export function _getPagesCountByParticlesCountInfinite({
+  particlesCountWithoutClones,
+  particlesToScroll,
+}) {
+  return Math.ceil(particlesCountWithoutClones / particlesToScroll)
+}
+
+export function _getPagesCountByParticlesCountLimited({
+  particlesCountWithoutClones,
+  particlesToScroll,
+}) {
+  return Math.round(particlesCountWithoutClones / particlesToScroll)
+}
+
 export function getPagesCountByParticlesCount({
   infinite,
   particlesCountWithoutClones,
   particlesToScroll,
 }) {
   return infinite
-    ? Math.ceil(particlesCountWithoutClones / particlesToScroll)
-    : Math.round(particlesCountWithoutClones / particlesToScroll)
+    ? _getPagesCountByParticlesCountInfinite({
+      particlesCountWithoutClones,
+      particlesToScroll,
+    })
+    : _getPagesCountByParticlesCountLimited({
+      particlesCountWithoutClones,
+      particlesToScroll,
+    })
 }
 
-export function getParticleIndexByPageIndexInfinite({
+// getParticleIndexByPageIndex
+
+export function _getParticleIndexByPageIndexInfinite({
   pageIndex,
   clonesCountHead,
   clonesCountTail,
@@ -63,13 +118,13 @@ export function getParticleIndexByPageIndexInfinite({
   particlesCount,
 }) {
   return getValueInRange(
-    clonesCountHead,
+    0,
     Math.min(clonesCountHead + pageIndex * particlesToScroll, particlesCount - clonesCountTail),
     particlesCount - 1
   )
 }
 
-export function getParticleIndexByPageIndexLimited({
+export function _getParticleIndexByPageIndexLimited({
   pageIndex,
   particlesToScroll,
   particlesCount,
@@ -92,14 +147,14 @@ export function getParticleIndexByPageIndex({
   particlesToShow,
 }) {
   return infinite
-    ? getParticleIndexByPageIndexInfinite({
+    ? _getParticleIndexByPageIndexInfinite({
       pageIndex,
       clonesCountHead,
       clonesCountTail,
       particlesToScroll,
       particlesCount,
     })
-    : getParticleIndexByPageIndexLimited({
+    : _getParticleIndexByPageIndexLimited({
       pageIndex,
       particlesToScroll,
       particlesCount,

src/utils/page.test.js

@@ -1,5 +1,6 @@
 import {
   getPartialPageSize,
+  _getCurrentPageIndexByCurrentParticleIndexInfinite
   // getCurrentPageIndex,
   // getPagesCountByParticlesCount,
   // getParticleIndexByPageIndexInfinite,
@@ -111,3 +112,124 @@ describe('getPartialPageSize', () => {
     })
   })
 })
+
+describe('_getCurrentPageIndexByCurrentParticleIndexInfinite', () => {
+  it('returns result as expected if particlesCount: 12; clonesCountHead: 2; clonesCountTotal: 5; particlesToScroll: 2', () => {
+    const testCases = [{
+      particlesCount: 12,
+      clonesCountHead: 2,
+      clonesCountTotal: 5,
+      particlesToScroll: 2,
+      currentParticleIndex: 0,
+      expected: 3,
+    }, {
+      particlesCount: 12,
+      clonesCountHead: 2,
+      clonesCountTotal: 5,
+      particlesToScroll: 2,
+      currentParticleIndex: 2,
+      expected: 0,
+    }, {
+      particlesCount: 12,
+      clonesCountHead: 2,
+      clonesCountTotal: 5,
+      particlesToScroll: 2,
+      currentParticleIndex: 4,
+      expected: 1,
+    }, {
+      particlesCount: 12,
+      clonesCountHead: 2,
+      clonesCountTotal: 5,
+      particlesToScroll: 2,
+      currentParticleIndex: 8,
+      expected: 3,
+    }, {
+      particlesCount: 12,
+      clonesCountHead: 2,
+      clonesCountTotal: 5,
+      particlesToScroll: 2,
+      currentParticleIndex: 10,
+      expected: 0,
+    }]
+
+    testCases.forEach(({
+      currentParticleIndex,
+      particlesCount,
+      clonesCountHead,
+      clonesCountTotal,
+      particlesToScroll,
+      expected,
+    }) => {
+      expect(_getCurrentPageIndexByCurrentParticleIndexInfinite({
+        currentParticleIndex,
+        particlesCount,
+        clonesCountHead,
+        clonesCountTotal,
+        particlesToScroll,
+      })).toBe(expected)
+    })
+  })
+
+  it('returns result as expected if particlesCount: 10; clonesCountHead: 1; clonesCountTotal: 3; particlesToScroll: 2', () => {
+    const testCases = [{
+      particlesCount: 10,
+      clonesCountHead: 1,
+      clonesCountTotal: 3,
+      particlesToScroll: 2,
+      currentParticleIndex: 0,
+      expected: 3,
+    }, {
+      particlesCount: 10,
+      clonesCountHead: 1,
+      clonesCountTotal: 3,
+      particlesToScroll: 2,
+      currentParticleIndex: 1,
+      expected: 0,
+    }, {
+      particlesCount: 10,
+      clonesCountHead: 1,
+      clonesCountTotal: 3,
+      particlesToScroll: 2,
+      currentParticleIndex: 3,
+      expected: 1,
+    }, {
+      particlesCount: 10,
+      clonesCountHead: 1,
+      clonesCountTotal: 3,
+      particlesToScroll: 2,
+      currentParticleIndex: 5,
+      expected: 2,
+    }, {
+      particlesCount: 10,
+      clonesCountHead: 1,
+      clonesCountTotal: 3,
+      particlesToScroll: 2,
+      currentParticleIndex: 7,
+      expected: 3,
+    }, {
+      particlesCount: 10,
+      clonesCountHead: 1,
+      clonesCountTotal: 3,
+      particlesToScroll: 2,
+      currentParticleIndex: 9,
+      expected: 0,
+    }]
+
+    testCases.forEach(({
+      currentParticleIndex,
+      particlesCount,
+      clonesCountHead,
+      clonesCountTotal,
+      particlesToScroll,
+      expected,
+    }) => {
+      expect(_getCurrentPageIndexByCurrentParticleIndexInfinite({
+        currentParticleIndex,
+        particlesCount,
+        clonesCountHead,
+        clonesCountTotal,
+        particlesToScroll,
+      })).toBe(expected)
+    })
+  })
+})