Tests/LibC: Add basic tests for strftime

Tests/LibC/CMakeLists.txt

@@ -35,6 +35,7 @@ set(TEST_SOURCES
     TestStackSmash.cpp
     TestStdio.cpp
     TestStpncpy.cpp
+    TestStrftime.cpp
     TestStrlcpy.cpp
     TestStrtodAccuracy.cpp
     TestTruncate.cpp

Tests/LibC/TestStrftime.cpp

@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2026, Lucas Chollet <[email protected]>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibTest/TestCase.h>
+#include <time.h>
+
+#pragma GCC diagnostic ignored "-Wformat-y2k"
+
+TEST_CASE(strftime)
+{
+    char str[200];
+    tm t;
+    t.tm_sec = 7;
+    t.tm_min = 53;
+    t.tm_hour = 11;
+    t.tm_mday = 10;
+    t.tm_mon = 9;
+    t.tm_year = 118;
+    t.tm_wday = 3;
+    t.tm_yday = 282;
+    t.tm_isdst = -1;
+
+    EXPECT(strftime(str, sizeof str, "The short name of the day of the week is %a.", &t));
+    EXPECT_EQ("The short name of the day of the week is Wed."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The full name of the day of the week is %A.", &t));
+    EXPECT_EQ("The full name of the day of the week is Wednesday."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The short name of the month is %b.", &t));
+    EXPECT_EQ("The short name of the month is Oct."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The full name of the month is %B.", &t));
+    EXPECT_EQ("The full name of the month is October."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The century is %C.", &t));
+    EXPECT_EQ("The century is 20."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The day of the month is %d.", &t));
+    EXPECT_EQ("The day of the month is 10."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The date is %D.", &t));
+    EXPECT_EQ("The date is 10/10/18."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The day of the month is %e.", &t));
+    EXPECT_EQ("The day of the month is 10."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The short name of the month is %h.", &t));
+    EXPECT_EQ("The short name of the month is Oct."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The hour is %H.", &t));
+    EXPECT_EQ("The hour is 11."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The hour is %I.", &t));
+    EXPECT_EQ("The hour is 11."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The day of the year is %j.", &t));
+    EXPECT_EQ("The day of the year is 283."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The number of the month is %m.", &t));
+    EXPECT_EQ("The number of the month is 10."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The minute is %M.", &t));
+    EXPECT_EQ("The minute is 53."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "This should be followed by a new line: %n.", &t));
+    EXPECT_EQ("This should be followed by a new line: \n."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The period of the day is %p.", &t));
+    EXPECT_EQ("The period of the day is AM."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The time is %r.", &t));
+    EXPECT_EQ("The time is 11:53:07 AM."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The time is %R.", &t));
+    EXPECT_EQ("The time is 11:53."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The second is %S.", &t));
+    EXPECT_EQ("The second is 07."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "This should be followed by a tab: %t.", &t));
+    EXPECT_EQ("This should be followed by a tab: \t."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The time is %T.", &t));
+    EXPECT_EQ("The time is 11:53:07."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The day of the week is %u.", &t));
+    EXPECT_EQ("The day of the week is 3."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The week of the year is %U.", &t));
+    EXPECT_EQ("The week of the year is 40."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The ISO week of the year is %V.", &t));
+    EXPECT_EQ("The ISO week of the year is 41."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The day of the week is %w.", &t));
+    EXPECT_EQ("The day of the week is 3."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The year is %y.", &t));
+    EXPECT_EQ("The year is 18."sv, str);
+
+    EXPECT(strftime(str, sizeof str, "The year is %Y.", &t));
+    EXPECT_EQ("The year is 2018."sv, str);
+}