Add TODOs to decade functions

date-fns · Jan 20, 2024 · e0a272d · e0a272d
1 parent c0aa54c
commit e0a272d
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Showing 8 changed files with 44 additions and 4 deletions.
diff --git a/src/endOfDecade/index.ts b/src/endOfDecade/index.ts
@@ -22,6 +22,9 @@ import { toDate } from "../toDate/index.js";
 export function endOfDecade<DateType extends Date>(
   date: DateType | number | string,
 ): DateType {
+  // TODO: Switch to more technical definition in of decades that start with 1
+  // end with 0. I.e. 2001-2010 instead of current 2000-2009. It's a breaking
+  // change, so it can only be done in 4.0.
   const _date = toDate(date);
   const year = _date.getFullYear();
   const decade = 9 + Math.floor(year / 10) * 10;

diff --git a/src/endOfDecade/test.ts b/src/endOfDecade/test.ts
@@ -1,7 +1,7 @@
 /* eslint-env mocha */
 
 import assert from "assert";
-import { describe, it } from "vitest";
+import { describe, expect, it } from "vitest";
 import { endOfDecade } from "./index.js";
 
 describe("endOfDecade", () => {
@@ -33,4 +33,13 @@ describe("endOfDecade", () => {
     const result = endOfDecade(new Date(NaN));
     assert(result instanceof Date && isNaN(result.getTime()));
   });
+
+  it("properly works with negative numbers", () => {
+    expect(endOfDecade(new Date(2001, 0, 1))).toEqual(
+      new Date(2009, 11, 31, 23, 59, 59, 999),
+    );
+    expect(endOfDecade(new Date(-2009, 0, 1))).toEqual(
+      new Date(-2001, 11, 31, 23, 59, 59, 999),
+    );
+  });
 });
diff --git a/src/getDecade/index.ts b/src/getDecade/index.ts
@@ -22,6 +22,9 @@ import { toDate } from "../toDate/index.js";
 export function getDecade<DateType extends Date>(
   date: DateType | number | string,
 ): number {
+  // TODO: Switch to more technical definition in of decades that start with 1
+  // end with 0. I.e. 2001-2010 instead of current 2000-2009. It's a breaking
+  // change, so it can only be done in 4.0.
   const _date = toDate(date);
   const year = _date.getFullYear();
   const decade = Math.floor(year / 10) * 10;

diff --git a/src/getDecade/test.ts b/src/getDecade/test.ts
@@ -1,7 +1,7 @@
 /* eslint-env mocha */
 
 import assert from "assert";
-import { describe, it } from "vitest";
+import { describe, expect, it } from "vitest";
 import { getDecade } from "./index.js";
 
 describe("getDecade", () => {
@@ -19,4 +19,9 @@ describe("getDecade", () => {
     const result = getDecade(new Date(NaN));
     assert(isNaN(result));
   });
+
+  it("properly works with negative numbers", () => {
+    expect(getDecade(new Date(2009, 0, 1))).toBe(2000);
+    expect(getDecade(new Date(-2001, 0, 1))).toBe(-2010);
+  });
 });
diff --git a/src/lastDayOfDecade/index.ts b/src/lastDayOfDecade/index.ts
@@ -22,6 +22,9 @@ import { toDate } from "../toDate/index.js";
 export function lastDayOfDecade<DateType extends Date>(
   date: DateType | number | string,
 ): DateType {
+  // TODO: Switch to more technical definition in of decades that start with 1
+  // end with 0. I.e. 2001-2010 instead of current 2000-2009. It's a breaking
+  // change, so it can only be done in 4.0.
   const _date = toDate(date);
   const year = _date.getFullYear();
   const decade = 9 + Math.floor(year / 10) * 10;

diff --git a/src/lastDayOfDecade/test.ts b/src/lastDayOfDecade/test.ts
@@ -1,7 +1,7 @@
 /* eslint-env mocha */
 
 import assert from "assert";
-import { describe, it } from "vitest";
+import { describe, expect, it } from "vitest";
 import { lastDayOfDecade } from "./index.js";
 
 describe("lastDayOfDecade", () => {
@@ -27,4 +27,13 @@ describe("lastDayOfDecade", () => {
     const result = lastDayOfDecade(new Date(NaN));
     assert(result instanceof Date && isNaN(result.getTime()));
   });
+
+  it("properly works with negative numbers", () => {
+    expect(lastDayOfDecade(new Date(2001, 0, 1))).toEqual(
+      new Date(2009, 11, 31),
+    );
+    expect(lastDayOfDecade(new Date(-2009, 0, 1))).toEqual(
+      new Date(-2001, 11, 31),
+    );
+  });
 });
diff --git a/src/startOfDecade/index.ts b/src/startOfDecade/index.ts
@@ -22,6 +22,9 @@ import { toDate } from "../toDate/index.js";
 export function startOfDecade<DateType extends Date>(
   date: DateType | number | string,
 ): DateType {
+  // TODO: Switch to more technical definition in of decades that start with 1
+  // end with 0. I.e. 2001-2010 instead of current 2000-2009. It's a breaking
+  // change, so it can only be done in 4.0.
   const _date = toDate(date);
   const year = _date.getFullYear();
   const decade = Math.floor(year / 10) * 10;

diff --git a/src/startOfDecade/test.ts b/src/startOfDecade/test.ts
@@ -1,7 +1,7 @@
 /* eslint-env mocha */
 
 import assert from "assert";
-import { describe, it } from "vitest";
+import { describe, expect, it } from "vitest";
 import { startOfDecade } from "./index.js";
 
 describe("startOfDecade", () => {
@@ -27,4 +27,9 @@ describe("startOfDecade", () => {
     const result = startOfDecade(new Date(NaN));
     assert(result instanceof Date && isNaN(result.getTime()));
   });
+
+  it("properly works with negative numbers", () => {
+    expect(startOfDecade(new Date(2009, 0, 1))).toEqual(new Date(2000, 0, 1));
+    expect(startOfDecade(new Date(-2001, 0, 1))).toEqual(new Date(-2010, 0, 1));
+  });
 });