fix NoSuchElementException in ViolationsUtil when no rules are evaluated

nebula-archrules-gradle-plugin/src/main/kotlin/com/netflix/nebula/archrules/gradle/ViolationsUtil.kt

@@ -56,7 +56,7 @@ class ViolationsUtil {
 
         @JvmStatic
         fun printSummary(resultMap: Map<Rule, List<RuleResult>>, output: StyledTextOutput) {
-            val maxRuleNameLength = resultMap.keys.maxOf { it.ruleName().length }
+            val maxRuleNameLength = resultMap.keys.maxOfOrNull { it.ruleName().length } ?: 1
             resultMap.forEach { (rule, results) ->
                 val failures = results.filter { it.status() != RuleResultStatus.PASS }
                 if (failures.isEmpty()) {

nebula-archrules-gradle-plugin/src/test/kotlin/com/netflix/nebula/archrules/gradle/ViolationsUtilTest.kt

@@ -0,0 +1,92 @@
+package com.netflix.nebula.archrules.gradle
+
+import com.tngtech.archunit.lang.Priority
+import org.assertj.core.api.Assertions.assertThat
+import org.gradle.internal.logging.text.StyledTextOutput
+import org.junit.jupiter.api.Test
+
+internal class ViolationsUtilTest {
+
+    @Test
+    fun `test printSummary`() {
+        val output = MockStyledTextOutput()
+        val rule = Rule("RuleClass", "RuleName", "description", Priority.MEDIUM)
+        val results = listOf(RuleResult(rule, "message", RuleResultStatus.PASS))
+        ViolationsUtil.printSummary(mapOf(rule to results), output)
+        assertThat(output.getOutput()).contains("RuleName  MEDIUM     (No failures)")
+    }
+
+    @Test
+    fun `test printSummary empty results`() {
+        val output = MockStyledTextOutput()
+        ViolationsUtil.printSummary(mapOf(), output)
+        assertThat(output.getOutput()).isEmpty()
+    }
+}
+
+class MockStyledTextOutput : StyledTextOutput {
+    private val output: StringBuilder = StringBuilder()
+    fun getOutput(): String = output.toString()
+    override fun append(c: Char): StyledTextOutput {
+        output.append(c)
+        return this
+    }
+
+    override fun append(csq: CharSequence?): StyledTextOutput {
+        output.append(csq)
+        return this
+    }
+
+    override fun append(
+        csq: CharSequence?,
+        start: Int,
+        end: Int
+    ): StyledTextOutput {
+        output.append(csq)
+        return this
+    }
+
+    override fun style(style: StyledTextOutput.Style?): StyledTextOutput {
+        return this
+    }
+
+    override fun withStyle(style: StyledTextOutput.Style?): StyledTextOutput {
+        return this
+    }
+
+    override fun text(text: Any?): StyledTextOutput {
+        output.append(text)
+        return this
+    }
+
+    override fun println(text: Any): StyledTextOutput {
+        output.append(text).append("\n")
+        return this
+    }
+
+    override fun format(
+        pattern: String?,
+        vararg args: Any?
+    ): StyledTextOutput {
+        output.append(pattern?.format(*args))
+        return this
+    }
+
+    override fun formatln(
+        pattern: String?,
+        vararg args: Any?
+    ): StyledTextOutput {
+        output.append(pattern?.format(*args)).append("\n")
+        return this
+    }
+
+    override fun println(): StyledTextOutput {
+        output.append("\n")
+        return this
+    }
+
+    override fun exception(throwable: Throwable?): StyledTextOutput {
+        TODO("Not yet implemented")
+    }
+
+}