fix: accept valid quarter-hour profile UTC offsets

src/auth/profile/dto/update-job-preferences.input.spec.ts

@@ -0,0 +1,48 @@
+import { ValidationPipe } from "@nestjs/common";
+import { UpdateJobPreferencesInput } from "./update-job-preferences.input";
+
+describe("Job preference UTC offset validation", () => {
+  const pipe = new ValidationPipe({ enableDebugMessages: false });
+  const validate = (utcOffset: unknown): Promise<UpdateJobPreferencesInput> =>
+    pipe.transform(
+      { workModes: ["remote"], utcOffset },
+      { type: "body", metatype: UpdateJobPreferencesInput },
+    );
+
+  it.each(Array.from({ length: 105 }, (_, index) => -12 + index / 4))(
+    "accepts UTC offset %s",
+    async utcOffset => {
+      await expect(validate(utcOffset)).resolves.toMatchObject({ utcOffset });
+    },
+  );
+
+  it.each(["3", "5.5", "5.75", "-3.5"])(
+    "accepts existing numeric string inputs for %s",
+    async utcOffset => {
+      await expect(validate(utcOffset)).resolves.toMatchObject({
+        utcOffset: Number(utcOffset),
+      });
+    },
+  );
+
+  it.each([null, undefined])("allows an unset offset (%s)", async utcOffset => {
+    await expect(validate(utcOffset)).resolves.toMatchObject({ utcOffset });
+  });
+
+  it.each([-12.25, 14.25, 3.1, 5.6, -3.3, 3.001, "invalid", NaN, Infinity])(
+    "rejects invalid UTC offset %s",
+    async utcOffset => {
+      await expect(validate(utcOffset)).rejects.toThrow();
+    },
+  );
+
+  it("explains the allowed increments for an invalid offset", async () => {
+    await expect(validate(3.1)).rejects.toMatchObject({
+      response: {
+        message: [
+          "UTC offset must use quarter-hour increments, such as 3, 5.5, or 5.75",
+        ],
+      },
+    });
+  });
+});

src/auth/profile/dto/update-job-preferences.input.ts

@@ -7,7 +7,6 @@ import {
   ArrayUnique,
   IsArray,
   IsBoolean,
-  IsDivisibleBy,
   IsIn,
   IsNumber,
   IsOptional,
@@ -26,6 +25,7 @@ import {
   WORK_MODES,
   WorkMode,
 } from "src/shared/interfaces";
+import { IsQuarterHourOffset } from "src/shared/validators/quarter-hour-offset.validator";
 
 const IsPreferenceList = (): ReturnType<typeof applyDecorators> =>
   applyDecorators(
@@ -58,7 +58,7 @@ export class UpdateJobPreferencesInput {
   @IsOptional()
   @Type(() => Number)
   @IsNumber({ maxDecimalPlaces: 2 })
-  @IsDivisibleBy(0.25)
+  @IsQuarterHourOffset()
   @Min(-12)
   @Max(14)
   utcOffset: number | null;

src/shared/validators/quarter-hour-offset.validator.ts

@@ -0,0 +1,20 @@
+import { ValidateBy, ValidationOptions } from "class-validator";
+
+export function IsQuarterHourOffset(
+  validationOptions?: ValidationOptions,
+): PropertyDecorator {
+  return ValidateBy(
+    {
+      name: "isQuarterHourOffset",
+      validator: {
+        // IsDivisibleBy truncates fractional divisors to integers. Scaling
+        // hours to quarter-hours avoids that and is exact for multiples of .25.
+        validate: (value: unknown): boolean =>
+          typeof value === "number" && Number.isInteger(value * 4),
+        defaultMessage: () =>
+          "UTC offset must use quarter-hour increments, such as 3, 5.5, or 5.75",
+      },
+    },
+    validationOptions,
+  );
+}