feat: perfect error handling

This commit perfects the error handling of the LotItemService and the
LotForm service.

client/src/modules/stock/LotItem.service.js

@@ -86,13 +86,20 @@ function LotItemService(uuid, $translate) {
    * register as expired.
    */
   Lot.prototype.validate = function validate(date) {
-    return this.hasInventoryInformation()
-      && this.hasLotInformation()
-      && !this.isUnused()
-      && !this.isExpired(date);
-  };
 
-  // Lot.prototype.
+    // we run all these individually to fill out the _errors conditions
+    const hasInventory = this.hasInventoryInformation();
+    const hasLot = this.hasLotInformation();
+    const isPositive = this.hasPositiveQuantity();
+    const isUsed = !this.isUnused();
+    const isNotExpired = !this.isExpired(date);
+
+    return hasInventory
+      && hasLot
+      && isPositive
+      && isUsed
+      && isNotExpired;
+  };
 
   // checks if a value is a uuid
   function isUuid(uid) {

test/client-unit/services/LotItemService.spec.js

@@ -204,6 +204,92 @@ describe('LotItemService', () => {
     expect(lot._errors).to.have.lengthOf(0);
   });
 
+  it('#isUnused() returns true stock available but unused', () => {
+    const lot = new Lot({ ...dataset[1] });
+    expect(lot.isUnused()).to.equal(false);
+    lot.quantity = 0;
+    expect(lot.isUnused()).to.equal(true);
+    lot.quantity = 1;
+    expect(lot.isUnused()).to.equal(false);
+  });
+
+  it('#hasPositiveQuantity() returns true if the quantity is strictly greater than 0', () => {
+    const lot = new Lot({ ...dataset[1] });
+    expect(lot.hasPositiveQuantity()).to.equal(true);
+    lot.quantity = 0;
+    expect(lot.hasPositiveQuantity()).to.equal(false);
+    lot.quantity = 1;
+    expect(lot.hasPositiveQuantity()).to.equal(true);
+    lot.quantity = -1;
+    expect(lot.hasPositiveQuantity()).to.equal(false);
+
+    // note that there is no upper-bound
+    lot.quantity = Infinity;
+    expect(lot.hasPositiveQuantity()).to.equal(true);
+  });
+
+  it('#hasEnoughQuantityAvailable() returns true if quantity less than total available', () => {
+    const lot = new Lot({ ...dataset[1] });
+
+    const initialQuantity = lot.quantity;
+    expect(lot.hasEnoughQuantityAvailable()).to.equal(true);
+
+    // set quantity to 0
+    lot.quantity = 0;
+    expect(lot.hasEnoughQuantityAvailable()).to.equal(true);
+
+    // set quantity to max possible
+    lot.quantity = initialQuantity;
+    expect(lot.hasEnoughQuantityAvailable()).to.equal(true);
+
+    // set quantity to one over max possible
+    lot.quantity = initialQuantity + 1;
+    expect(lot.hasEnoughQuantityAvailable()).to.equal(false);
+  });
+
+  it('#errors() returns a list of error codes', () => {
+    const example = { ...dataset[0] };
+    delete example.is_expired;
+
+    const futureDate = new Date('2222-01-01');
+    const lot = new Lot(example);
+
+    expect(lot.errors()).to.have.lengthOf(0);
+
+    // set a past date as the comparison to determine expiration
+    expect(lot.isExpired(futureDate)).to.equal(true);
+    expect(lot.errors()).to.deep.equal(['STOCK.ERRORS.LOT_EXPIRED']);
+
+    // set an invalid quantity
+    lot.quantity = -1;
+    expect(lot.hasPositiveQuantity()).to.equal(false);
+    expect(lot.errors()).to.deep.equal(['STOCK.ERRORS.LOT_EXPIRED', 'STOCK.ERRORS.LOT_NEGATIVE_QUANTITY']);
+
+    // recompute the expiration date to leave only a single error
+    expect(lot.isExpired()).to.equal(false);
+    expect(lot.errors()).to.deep.equal(['STOCK.ERRORS.LOT_NEGATIVE_QUANTITY']);
+
+    // restore quantity and recompute validation.
+    lot.quantity = 1;
+    expect(lot.validate()).to.equal(true);
+    expect(lot.errors()).to.deep.equal([]);
+
+    // screw everything up and check error codes
+    lot.quantity = -10;
+    delete lot.inventory_uuid;
+    delete lot.label;
+
+    // these error codes are stored in a Set() so they are returned
+    // in the order they are inserted.
+    expect(lot.validate(futureDate)).to.equal(false);
+    expect(lot.errors()).to.deep.equal([
+      'STOCK.ERRORS.LOT_MISSING_INVENTORY_INFO',
+      'STOCK.ERRORS.LOT_MISSING_LOT_INFO',
+      'STOCK.ERRORS.LOT_NEGATIVE_QUANTITY',
+      'STOCK.ERRORS.LOT_EXPIRED',
+    ]);
+  });
+
   it('#validate() returns true for a valid inventory', () => {
     const lot = new Lot(dataset[1]);