From f2b29507760c615dd7967873b458fb95466566cb Mon Sep 17 00:00:00 2001
From: Tommaso Sebastianelli <tommaso-sebastianelli@users.noreply.github.com>
Date: Wed, 7 Feb 2024 17:02:44 +0100
Subject: [PATCH] fix: include undefined values if formatting with zero option
 set to true

---
 src/formatDuration/index.ts |  2 +-
 src/formatDuration/test.ts  | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/src/formatDuration/index.ts b/src/formatDuration/index.ts
index 08a8ff9095..2f3586950b 100644
--- a/src/formatDuration/index.ts
+++ b/src/formatDuration/index.ts
@@ -105,7 +105,7 @@ export function formatDuration(
       const token = `x${unit.replace(/(^.)/, (m) =>
         m.toUpperCase(),
       )}` as FormatDistanceToken;
-      const value = duration[unit];
+      const value = duration[unit] ?? (zero ? 0 : undefined);
       if (value !== undefined && (zero || duration[unit])) {
         return acc.concat(locale.formatDistance(token, value));
       }
diff --git a/src/formatDuration/test.ts b/src/formatDuration/test.ts
index af7aad2097..711ce92e3e 100644
--- a/src/formatDuration/test.ts
+++ b/src/formatDuration/test.ts
@@ -77,4 +77,38 @@ describe("formatDuration", () => {
         "9 months, 2 days",
     );
   });
+
+  it("allows to provide a custom locale formatter", () => {
+    assert(
+      formatDuration(
+        {
+          hours: 1,
+          minutes: 10,
+          seconds: 30,
+        },
+        {
+          delimiter: ":",
+          format: ["hours", "minutes", "seconds"],
+          locale: {
+            formatDistance: (_, count) => String(count).padStart(2, "0"),
+          },
+          zero: true,
+        },
+      ) === "01:10:30",
+    );
+  });
+
+  it("includes undefined duration values when formatting if zero is true", () => {
+    assert(
+      formatDuration(
+        {
+          seconds: 10,
+        },
+        {
+          format: ["hours", "minutes", "seconds"],
+          zero: true,
+        },
+      ) === "0 hours 0 minutes 10 seconds",
+    );
+  });
 });