fix(scaling): default servings 1 if no servings defined

Author: tmlmt

docs/examples-scaling-recipes.md

@@ -6,7 +6,7 @@ outline: deep
 
 ## Pre-requisite
 
-To be able to scale, a `Recipe` must have its [`servings`](/api/classes/Recipe.html#servings) property set, which is done by the parser when it encounters
+To be able to scale, `Recipe` uses its [`servings`](/api/classes/Recipe.html#servings) property, which is done by the parser when it encounters
 one of the following tags in the recipe's frontmatter: [`servings`](/api/interfaces/Metadata.html#servings), [`serves`](/api/interfaces/Metadata.html#serves) or [`yield`](/api/interfaces/Metadata.html#yield):
 
 ```json
@@ -17,7 +17,7 @@ servings: 2
 ---
 ```
 
-The rest of this guide assumes that you have set one of the above, and will assume a `servings` value of `2`
+If none of those are found and the `servings` property is undefined, it will default to 1 when scaling. The rest of this guide assumes that you have set one of the above, and will assume a `servings` value of `2`
 
 ## Scaling by a factor
 

src/classes/recipe.ts

@@ -1120,10 +1120,11 @@ export class Recipe {
    * @throws `Error` if the recipe does not contains an initial {@link Recipe.servings | servings} value
    */
   scaleTo(newServings: number): Recipe {
-    const originalServings = this.getServings();
+    let originalServings = this.getServings();
 
+    // Default to 1 if no servings defined
     if (originalServings === undefined || originalServings === 0) {
-      throw new Error("Error scaling recipe: no initial servings value set");
+      originalServings = 1;
     }
 
     const factor = Big(newServings).div(originalServings);
@@ -1139,10 +1140,11 @@ export class Recipe {
   scaleBy(factor: number | Big): Recipe {
     const newRecipe = this.clone();
 
-    const originalServings = newRecipe.getServings();
+    let originalServings = newRecipe.getServings();
 
+    // Default to 1 if no servings defined
     if (originalServings === undefined || originalServings === 0) {
-      throw new Error("Error scaling recipe: no initial servings value set");
+      originalServings = 1;
     }
 
     function scaleAlternativesBy(

test/recipe_scaling.test.ts

@@ -125,29 +125,21 @@ describe("scaleTo", () => {
     });
   });
 
-  it("should throw an error if no initial servings information", () => {
-    const recipeWithoutServings = new Recipe();
-    recipeWithoutServings.ingredients = [
-      {
-        name: "water",
-        quantities: [
-          {
-            groupQuantity: {
-              quantity: {
-                type: "fixed",
-                value: { type: "decimal", decimal: 1 },
-              },
-              unit: "l",
-            },
-          },
-        ],
-        flags: [],
+  it("should default servings to 1 if no initial servings information", () => {
+    const recipeWithoutServings = new Recipe("@water{1%L}");
+    const scaledRecipe = recipeWithoutServings.scaleTo(4);
+    expect(scaledRecipe.servings).toBe(4);
+    const water = scaledRecipe.ingredients[0]!.quantities;
+    if (!water) throw new Error("No quantities found for water ingredient");
+    expect(water[0]).toEqual({
+      groupQuantity: {
+        quantity: {
+          type: "fixed",
+          value: { type: "decimal", decimal: 4 },
+        },
+        unit: "L",
       },
-    ];
-
-    expect(() => recipeWithoutServings.scaleTo(4)).toThrowError(
-      "Error scaling recipe: no initial servings value set",
-    );
+    });
   });
 
   it("should not modify the original recipe", () => {
@@ -292,30 +284,21 @@ describe("scaleBy", () => {
     expect(scaledRecipe.metadata.yield).toBe("4");
   });
 
-  it("should throw an error if no initial serving information", () => {
-    const recipeWithoutServings = new Recipe();
-    recipeWithoutServings.metadata = {};
-    recipeWithoutServings.ingredients = [
-      {
-        name: "water",
-        quantities: [
-          {
-            groupQuantity: {
-              quantity: {
-                type: "fixed",
-                value: { type: "decimal", decimal: 1 },
-              },
-              unit: "l",
-            },
-          },
-        ],
-        flags: [],
+  it("should default servings to 1 if no initial serving information", () => {
+    const recipeWithoutServings = new Recipe("@water{1%L}");
+    const scaledRecipe = recipeWithoutServings.scaleBy(2);
+    expect(scaledRecipe.servings).toBe(2);
+    const water = scaledRecipe.ingredients[0]!.quantities;
+    if (!water) throw new Error("No quantities found for water ingredient");
+    expect(water[0]).toEqual({
+      groupQuantity: {
+        quantity: {
+          type: "fixed",
+          value: { type: "decimal", decimal: 2 },
+        },
+        unit: "L",
       },
-    ];
-
-    expect(() => recipeWithoutServings.scaleBy(2)).toThrowError(
-      "Error scaling recipe: no initial servings value set",
-    );
+    });
   });
 
   it("should not modify the original recipe", () => {