feat: add Å to SI accepted units

src/common/utils.spec.ts

@@ -0,0 +1,47 @@
+// Currently only covers converToSI
+import { convertToSI } from "./utils";
+
+describe("convertToSI", () => {
+  it("should convert a known unit to SI successfully", () => {
+    const result = convertToSI(1, "cm");
+    expect(result.valueSI).toBeCloseTo(0.01);
+    expect(result.unitSI).toEqual("m");
+  });
+
+  it("should convert angstrom to SI successfully", () => {
+    const result = convertToSI(1, "Å");
+    expect(result.valueSI).toBeCloseTo(1e-10);
+    expect(result.unitSI).toEqual("m");
+  });
+
+  it("should handle different versions of Å in unicode", () => {
+    const inputUnit = "\u212B"; // Old unicode representation of "Å", is not boolean equal to the one we added.
+    const result = convertToSI(1, inputUnit);
+    expect(result.valueSI).toBeCloseTo(1e-10);
+    expect(result.unitSI).toEqual("m");
+  });
+
+  it("should return the input value and unit if conversion fails", () => {
+    const result = convertToSI(1, "invalidUnit");
+    expect(result.valueSI).toEqual(1);
+    expect(result.unitSI).toEqual("invalidUnit");
+  });
+
+  it("should convert SI units correctly", () => {
+    const result = convertToSI(1000, "g");
+    expect(result.valueSI).toBeCloseTo(1);
+    expect(result.unitSI).toEqual("kg");
+  });
+
+  it("should handle already normalized units", () => {
+    const result = convertToSI(1, "m");
+    expect(result.valueSI).toEqual(1);
+    expect(result.unitSI).toEqual("m");
+  });
+
+  it("should handle negative values properly", () => {
+    const result = convertToSI(-5, "cm");
+    expect(result.valueSI).toBeCloseTo(-0.05);
+    expect(result.unitSI).toEqual("m");
+  });
+});

src/common/utils.ts

@@ -2,7 +2,7 @@
 import { Logger } from "@nestjs/common";
 import { inspect } from "util";
 import { DateTime } from "luxon";
-import { format, unit } from "mathjs";
+import { format, unit, Unit, createUnit } from "mathjs";
 import { Expression, FilterQuery, Model, PipelineStage } from "mongoose";
 import { DatasetType } from "src/datasets/dataset-type.enum";
 import {
@@ -13,14 +13,22 @@ import {
 } from "./interfaces/common.interface";
 import { ScientificRelation } from "./scientific-relation.enum";
 
+// add Å to mathjs accepted units as equivalent to angstrom
+const isAlphaOriginal = Unit.isValidAlpha;
+Unit.isValidAlpha = function (c) {
+  return isAlphaOriginal(c) || c == "Å";
+};
+createUnit("Å", "1 angstrom");
+
 export const convertToSI = (
   inputValue: number,
   inputUnit: string,
 ): { valueSI: number; unitSI: string } => {
   try {
+    const normalizedUnit = inputUnit.normalize("NFC"); // catch and normalize the different versions of Å in unicode
     // Workaround related to a bug reported at https://github.com/josdejong/mathjs/issues/3097 and https://github.com/josdejong/mathjs/issues/2499
-    const quantity = unit(inputValue, inputUnit)
-      .to(unit(inputUnit).toSI().toJSON().unit)
+    const quantity = unit(inputValue, normalizedUnit)
+      .to(unit(normalizedUnit).toSI().toJSON().unit)
       .toJSON();
     return { valueSI: Number(quantity.value), unitSI: quantity.unit };
   } catch (error) {