fix: consolidate essence formatting into single shared function (Closes #80) (#122)

sharedUI/src/commonMain/kotlin/org/shahondin1624/lib/components/charactermodel/CharacterDataEditDialog.kt

@@ -11,6 +11,7 @@ import androidx.compose.ui.platform.testTag
 import androidx.compose.ui.text.input.KeyboardType
 import androidx.compose.ui.unit.dp
 import org.shahondin1624.lib.components.TestTags
+import org.shahondin1624.lib.functions.formatEssence
 import org.shahondin1624.model.characterdata.CharacterData
 import org.shahondin1624.model.characterdata.Metatype
 
@@ -31,7 +32,7 @@ fun CharacterDataEditDialog(
     var metatype by remember { mutableStateOf(characterData.metatype) }
     var ageText by remember { mutableStateOf(characterData.age.toString()) }
     var nuyenText by remember { mutableStateOf(characterData.nuyen.toString()) }
-    var essenceText by remember { mutableStateOf(formatEssenceForEdit(characterData.essence)) }
+    var essenceText by remember { mutableStateOf(formatEssence(characterData.essence)) }
     var totalKarmaText by remember { mutableStateOf(characterData.totalKarma.toString()) }
     var currentKarmaText by remember { mutableStateOf(characterData.currentKarma.toString()) }
 
@@ -229,12 +230,3 @@ fun CharacterDataEditDialog(
         }
     )
 }
-
-/**
- * Format essence float for editing, showing one decimal place.
- */
-private fun formatEssenceForEdit(essence: Float): String {
-    val wholePart = essence.toInt()
-    val decimalPart = ((essence - wholePart) * 10 + 0.5f).toInt()
-    return "$wholePart.$decimalPart"
-}

sharedUI/src/commonMain/kotlin/org/shahondin1624/lib/components/charactermodel/ResourcePanel.kt

@@ -12,20 +12,10 @@ import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
 import org.shahondin1624.lib.components.TestTags
 import org.shahondin1624.lib.components.UiConstants
+import org.shahondin1624.lib.functions.formatEssence
 import org.shahondin1624.model.characterdata.CharacterData
 import org.shahondin1624.theme.LocalWindowSizeClass
 import org.shahondin1624.theme.WindowSizeClass
-import kotlin.math.roundToInt
-
-/**
- * Formats a float to one decimal place without platform-specific String.format.
- */
-private fun formatEssence(value: Float): String {
-    val rounded = (value * 10).roundToInt() / 10.0
-    val intPart = rounded.toInt()
-    val decPart = ((rounded - intPart) * 10).roundToInt()
-    return "$intPart.$decPart"
-}
 
 /**
  * Displays resource trackers: Karma (current/total), Nuyen, Essence, and Edge.

sharedUI/src/commonMain/kotlin/org/shahondin1624/lib/functions/Formatting.kt

@@ -0,0 +1,16 @@
+package org.shahondin1624.lib.functions
+
+import kotlin.math.roundToInt
+
+/**
+ * Formats a float to one decimal place without platform-specific String.format.
+ * Uses integer rounding to avoid floating-point precision artifacts.
+ *
+ * Examples: 5.7f -> "5.7", 6.0f -> "6.0", 0.0f -> "0.0"
+ */
+fun formatEssence(value: Float): String {
+    val rounded = (value * 10).roundToInt() / 10.0
+    val intPart = rounded.toInt()
+    val decPart = ((rounded - intPart) * 10).roundToInt()
+    return "$intPart.$decPart"
+}

sharedUI/src/commonTest/kotlin/org/shahondin1624/FormatEssenceTest.kt

@@ -0,0 +1,59 @@
+package org.shahondin1624
+
+import org.shahondin1624.lib.functions.formatEssence
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class FormatEssenceTest {
+
+    @Test
+    fun formatsWholeNumber() {
+        assertEquals("6.0", formatEssence(6.0f))
+    }
+
+    @Test
+    fun formatsZero() {
+        assertEquals("0.0", formatEssence(0.0f))
+    }
+
+    @Test
+    fun formatsTypicalEssenceValue() {
+        assertEquals("5.7", formatEssence(5.7f))
+    }
+
+    @Test
+    fun formatsOneDecimalPlace() {
+        assertEquals("3.5", formatEssence(3.5f))
+    }
+
+    @Test
+    fun roundsFloatingPointPrecisionArtifacts() {
+        // 5.7f may be stored as 5.6999998 internally
+        assertEquals("5.7", formatEssence(5.6999998f))
+    }
+
+    @Test
+    fun formatsSmallFractionalValue() {
+        assertEquals("0.1", formatEssence(0.1f))
+    }
+
+    @Test
+    fun formatsLargeFractionalValue() {
+        assertEquals("5.9", formatEssence(5.9f))
+    }
+
+    @Test
+    fun roundsUpCorrectly() {
+        assertEquals("2.3", formatEssence(2.25f))
+    }
+
+    @Test
+    fun roundsDownCorrectly() {
+        assertEquals("2.2", formatEssence(2.24f))
+    }
+
+    @Test
+    fun formatsMaxEssence() {
+        assertEquals("6.0", formatEssence(6.0f))
+    }
+}