Updated on 2026-08-14

core/ui/src/test/kotlin/com/tangem/core/ui/utils/DateTimeFormattersTest.kt

@@ -0,0 +1,143 @@
+package com.tangem.core.ui.utils
+
+import com.google.common.truth.Truth
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.TestInstance
+
+/**
+ * Unit tests for [DateTimeFormatters], in particular for conversion of ICU date/time patterns
+ * to Joda-Time compatible patterns.
+ */
+@TestInstance(TestInstance.Lifecycle.PER_CLASS)
+class DateTimeFormattersTest {
+
+    @Test
+    fun `converts LLLL to MMMM - full standalone month pattern that crashes on Chinese locale`() {
+        // Arrange
+        val icuPattern = "d LLLL"
+
+        // Act
+        val actual = DateTimeFormatters.icuPatternToJodaPattern(icuPattern)
+
+        // Assert
+        Truth.assertThat(actual).isEqualTo("d MMMM")
+    }
+
+    @Test
+    fun `converts LLL to MMM - short standalone month`() {
+        // Arrange
+        val icuPattern = "dd LLL yyyy"
+
+        // Act
+        val actual = DateTimeFormatters.icuPatternToJodaPattern(icuPattern)
+
+        // Assert
+        Truth.assertThat(actual).isEqualTo("dd MMM yyyy")
+    }
+
+    @Test
+    fun `converts LL to MM - numeric standalone month`() {
+        // Arrange
+        val icuPattern = "yyyy-MM-LL"
+
+        // Act
+        val actual = DateTimeFormatters.icuPatternToJodaPattern(icuPattern)
+
+        // Assert
+        Truth.assertThat(actual).isEqualTo("yyyy-MM-MM")
+    }
+
+    @Test
+    fun `converts single L to M`() {
+        // Arrange
+        val icuPattern = "d/L/yyyy"
+
+        // Act
+        val actual = DateTimeFormatters.icuPatternToJodaPattern(icuPattern)
+
+        // Assert
+        Truth.assertThat(actual).isEqualTo("d/M/yyyy")
+    }
+
+    @Test
+    fun `leaves pattern without L unchanged`() {
+        // Arrange
+        val icuPattern = "dd.MM.yyyy HH:mm"
+
+        // Act
+        val actual = DateTimeFormatters.icuPatternToJodaPattern(icuPattern)
+
+        // Assert
+        Truth.assertThat(actual).isEqualTo("dd.MM.yyyy HH:mm")
+    }
+
+    @Test
+    fun `leaves pattern with M unchanged`() {
+        // Arrange
+        val icuPattern = "d MMMM yyyy"
+
+        // Act
+        val actual = DateTimeFormatters.icuPatternToJodaPattern(icuPattern)
+
+        // Assert
+        Truth.assertThat(actual).isEqualTo("d MMMM yyyy")
+    }
+
+    @Test
+    fun `handles mixed ICU pattern as returned for Chinese locale - d MMMM`() {
+        // Arrange
+        val icuPatternWithStandaloneMonth = "d LLLL"
+
+        // Act
+        val actual = DateTimeFormatters.icuPatternToJodaPattern(icuPatternWithStandaloneMonth)
+
+        // Assert — Joda-Time can parse and format this without IllegalArgumentException
+        Truth.assertThat(actual).isEqualTo("d MMMM")
+    }
+
+    @Test
+    fun `handles empty string`() {
+        // Arrange
+        val icuPattern = ""
+
+        // Act
+        val actual = DateTimeFormatters.icuPatternToJodaPattern(icuPattern)
+
+        // Assert
+        Truth.assertThat(actual).isEmpty()
+    }
+
+    @Test
+    fun `handles pattern with only literal characters`() {
+        // Arrange
+        val icuPattern = " 'at' "
+
+        // Act
+        val actual = DateTimeFormatters.icuPatternToJodaPattern(icuPattern)
+
+        // Assert
+        Truth.assertThat(actual).isEqualTo(" 'at' ")
+    }
+
+    @Test
+    fun `getBestFormatterBySkeleton with d MMMM skeleton produces formatter that does not throw on format`() {
+        // Arrange
+        val formatter = DateTimeFormatters.getBestFormatterBySkeleton("d MMMM")
+        val date = org.joda.time.DateTime(2025, 2, 13, 12, 0, 0, 0)
+
+        // Act & Assert
+        val formatted = formatter.print(date)
+        Truth.assertThat(formatted).isNotEmpty()
+    }
+
+    @Test
+    fun `getBestFormatterBySkeleton with dd MMMM skeleton produces formatter that does not throw on format`() {
+        // Arrange
+        val formatter = DateTimeFormatters.getBestFormatterBySkeleton("dd MMMM")
+        val date = org.joda.time.DateTime(2025, 2, 13, 12, 0, 0, 0)
+
+        // Act & Assert
+        val formatted = formatter.print(date)
+        Truth.assertThat(formatted).isNotEmpty()
+    }
+}