Fix bullet graph exception when using more than 4 qualitative ranges.

CHANGELOG.md

@@ -18,11 +18,15 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - Upgrade Kotlin to 2.1.0
 - Android Gradle Plugin to 8.7.2
 - Android compileSDK to 34 and minSDK to 23
+- BulletGraph using default qualitative range indicators will accept a max of 5 values when being configured rather
+  than throwing a null pointer exception when Composing.
 
 ### Fixed
 
 - Panning support for Int and Long linear axis models by introducing ContinuousLinearAxisModel and
   DiscreteLinearAxisModel interfaces
+- BulletGraph null pointer exception if more than 4 qualitative range indicators are used.
+- BulletGraph qualitative range default shading not according to spec under some conditions.
 
 ## [0.7.1]
 

src/commonMain/kotlin/io/github/koalaplot/core/bar/BulletBuilderScope.kt

@@ -61,6 +61,9 @@ private val DefaultRangeShades = listOf(
     listOf(0.5f, 0.65f, 0.8f, 0.9f, 0.97f),
 )
 
+// Max number of qualitative ranges supported by the DefaultRangeShades above
+private const val MaxQualitativeRanges = 5
+
 private const val MinRangeShade = 0.99f
 
 /**
@@ -174,6 +177,11 @@ public class BulletBuilderScope<T>(private val axisModel: LinearAxisModel<T>) wh
      * to be customized then use the overloaded version of this function.
      */
     public fun ranges(vararg values: T) {
+        // Subtract 1 because first value is the start of first range, not a range itself
+        require(values.size - 1 <= MaxQualitativeRanges) {
+            "A maximum of $MaxQualitativeRanges qualitative ranges is supported by this function. If more are " +
+                "required, use the overloaded version of this function."
+        }
         rangesScope = RangesScope<T>().apply {
             values.forEach {
                 ranges.add(Range<T>(it, null))
@@ -358,11 +366,12 @@ public class BulletBuilderScope<T>(private val axisModel: LinearAxisModel<T>) wh
         @OptIn(ExperimentalKoalaPlotApi::class)
         @Composable
         private fun <T> RangeIndicators(builtScope: BulletBuilderScope<T>) where T : Comparable<T>, T : Number {
-            val shadeIndex = max(builtScope.rangesScope.ranges.size - 1, DefaultRangeShades.lastIndex)
-            val numShades = DefaultRangeShades[shadeIndex].size
             for (rangeIndex in 1 until builtScope.rangesScope.ranges.size) {
                 val range = builtScope.rangesScope.ranges[rangeIndex]
                 if (range.indicator == null) {
+                    val shadeIndex = min(builtScope.rangesScope.ranges.size - 2, DefaultRangeShades.lastIndex)
+                        .coerceIn(0..DefaultRangeShades.lastIndex)
+                    val numShades = DefaultRangeShades[shadeIndex].size
                     val shade = if (rangeIndex - 1 >= numShades) {
                         MinRangeShade
                     } else {

src/desktopTest/kotlin/io/github/koalaplot/core/bar/BulletGraphTest.kt

@@ -0,0 +1,83 @@
+package io.github.koalaplot.core.bar
+
+import androidx.compose.ui.test.junit4.createComposeRule
+import io.github.koalaplot.core.util.ExperimentalKoalaPlotApi
+import io.github.koalaplot.core.xygraph.IntLinearAxisModel
+import org.junit.Rule
+import org.junit.Test
+
+class BulletGraphTest {
+    @get:Rule
+    val composeTestRule = createComposeRule()
+
+    /**
+     * 5 default qualitative ranges allowed.
+     */
+    @OptIn(ExperimentalKoalaPlotApi::class)
+    @Suppress("MagicNumber")
+    @Test
+    fun fiveDefaultRangesTest() {
+        composeTestRule.setContent {
+            BulletGraphs {
+                bullet(
+                    IntLinearAxisModel(0..100)
+                ) {
+                    ranges(0, 10, 20, 30, 40, 50)
+
+                }
+            }
+        }
+    }
+
+    /**
+     * Trying to use more than 5 qualitative ranges should fail with an IllegalArgumentException.
+     */
+    @OptIn(ExperimentalKoalaPlotApi::class)
+    @Suppress("MagicNumber")
+    @Test
+    fun moreThanFiveDefaultRangesFailsTest() {
+        composeTestRule.setContent {
+            var caught = false
+
+            BulletGraphs {
+                bullet(
+                    IntLinearAxisModel(0..100)
+                ) {
+                    try {
+                        ranges(0, 10, 20, 30, 40, 50, 60)
+                    } catch (_: IllegalArgumentException) {
+                        caught = true
+                    }
+                }
+            }
+
+            assert(caught)
+        }
+    }
+
+    /**
+     *
+     */
+    @OptIn(ExperimentalKoalaPlotApi::class)
+    @Suppress("MagicNumber")
+    @Test
+    fun moreThanFiveCustomRangesTest() {
+        composeTestRule.setContent {
+            BulletGraphs {
+                bullet(
+                    IntLinearAxisModel(0..100)
+                ) {
+
+                    ranges(0) {
+                        range(10)
+                        range(20)
+                        range(30)
+                        range(40)
+                        range(50)
+                        range(60)
+                    }
+                }
+            }
+        }
+    }
+}