Add cognitive complexity in complexity report (#2727)

* Add metric processor for cognitive complexity

* Add cognitive complexity to complexity report

detekt-cli/src/main/kotlin/io/gitlab/arturbosch/detekt/cli/console/ComplexityMetric.kt

@@ -1,5 +1,6 @@
 package io.gitlab.arturbosch.detekt.cli.console
 
+import io.github.detekt.metrics.CognitiveComplexity
 import io.gitlab.arturbosch.detekt.api.Detektion
 import io.github.detekt.metrics.processors.commentLinesKey
 import io.github.detekt.metrics.processors.complexityKey
@@ -10,6 +11,7 @@ import io.github.detekt.metrics.processors.sourceLinesKey
 class ComplexityMetric(detektion: Detektion) {
 
     val mcc = detektion.getData(complexityKey)
+    val cognitiveComplexity = detektion.getData(CognitiveComplexity.KEY)
     val loc = detektion.getData(linesKey)
     val sloc = detektion.getData(sourceLinesKey)
     val lloc = detektion.getData(logicalLinesKey)

detekt-cli/src/main/kotlin/io/gitlab/arturbosch/detekt/cli/console/ComplexityReportGenerator.kt

@@ -22,7 +22,8 @@ class ComplexityReportGenerator(private val complexityMetric: ComplexityMetric)
             "%,d source lines of code (sloc)".format(Locale.US, complexityMetric.sloc),
             "%,d logical lines of code (lloc)".format(Locale.US, complexityMetric.lloc),
             "%,d comment lines of code (cloc)".format(Locale.US, complexityMetric.cloc),
-            "%,d McCabe complexity (mcc)".format(Locale.US, complexityMetric.mcc),
+            "%,d cyclomatic complexity (mcc)".format(Locale.US, complexityMetric.mcc),
+            "%,d cognitive complexity".format(Locale.US, complexityMetric.cognitiveComplexity),
             "%,d number of total code smells".format(Locale.US, numberOfSmells),
             "%,d%% comment source ratio".format(Locale.US, commentSourceRatio),
             "%,d mcc per 1,000 lloc".format(Locale.US, mccPerThousandLines),
@@ -32,15 +33,18 @@ class ComplexityReportGenerator(private val complexityMetric: ComplexityMetric)
 
     private fun cannotGenerate(): Boolean {
         return when {
-            complexityMetric.mcc == null -> true
+            null in setOf(
+                complexityMetric.mcc,
+                complexityMetric.cloc,
+                complexityMetric.cognitiveComplexity
+            ) -> true
             complexityMetric.lloc == null || complexityMetric.lloc == 0 -> true
             complexityMetric.sloc == null || complexityMetric.sloc == 0 -> true
-            complexityMetric.cloc == null -> true
             else -> {
                 numberOfSmells = complexityMetric.findings.sumBy { it.value.size }
                 smellPerThousandLines = numberOfSmells * 1000 / complexityMetric.lloc
-                mccPerThousandLines = complexityMetric.mcc * 1000 / complexityMetric.lloc
-                commentSourceRatio = complexityMetric.cloc * 100 / complexityMetric.sloc
+                mccPerThousandLines = complexityMetric.mcc!! * 1000 / complexityMetric.lloc
+                commentSourceRatio = complexityMetric.cloc!! * 100 / complexityMetric.sloc
                 false
             }
         }

detekt-cli/src/main/resources/META-INF/services/io.gitlab.arturbosch.detekt.api.FileProcessListener

@@ -5,6 +5,7 @@ io.github.detekt.metrics.processors.ClassCountProcessor
 io.github.detekt.metrics.processors.FunctionCountProcessor
 io.github.detekt.metrics.processors.PropertyCountProcessor
 io.github.detekt.metrics.processors.ProjectComplexityProcessor
+io.github.detekt.metrics.processors.ProjectCognitiveComplexityProcessor
 io.github.detekt.metrics.processors.ProjectLLOCProcessor
 io.github.detekt.metrics.processors.ProjectCLOCProcessor
 io.github.detekt.metrics.processors.ProjectLOCProcessor

detekt-cli/src/test/kotlin/io/gitlab/arturbosch/detekt/cli/console/ComplexityReportGeneratorSpec.kt

@@ -1,5 +1,6 @@
 package io.gitlab.arturbosch.detekt.cli.console
 
+import io.github.detekt.metrics.CognitiveComplexity
 import io.gitlab.arturbosch.detekt.api.Detektion
 import io.gitlab.arturbosch.detekt.cli.createFinding
 import io.github.detekt.metrics.processors.commentLinesKey
@@ -31,7 +32,8 @@ internal class ComplexityReportGeneratorSpec : Spek({
                     "6 source lines of code (sloc)",
                     "5 logical lines of code (lloc)",
                     "4 comment lines of code (cloc)",
-                    "2 McCabe complexity (mcc)",
+                    "2 cyclomatic complexity (mcc)",
+                    "2 cognitive complexity",
                     "1 number of total code smells",
                     "66% comment source ratio",
                     "400 mcc per 1,000 lloc",
@@ -75,6 +77,7 @@ internal class ComplexityReportGeneratorSpec : Spek({
 
 private fun addData(detektion: Detektion) {
     detektion.addData(complexityKey, 2)
+    detektion.addData(CognitiveComplexity.KEY, 2)
     detektion.addData(linesKey, 1000)
     detektion.addData(sourceLinesKey, 6)
     detektion.addData(logicalLinesKey, 5)

detekt-cli/src/test/kotlin/io/gitlab/arturbosch/detekt/cli/console/ComplexityReportSpec.kt

@@ -1,5 +1,6 @@
 package io.gitlab.arturbosch.detekt.cli.console
 
+import io.github.detekt.metrics.CognitiveComplexity
 import io.gitlab.arturbosch.detekt.api.Detektion
 import io.gitlab.arturbosch.detekt.cli.createFinding
 import io.gitlab.arturbosch.detekt.core.DetektResult
@@ -23,9 +24,7 @@ internal class ComplexityReportSpec : Spek({
                 val expectedContent = readResource("complexity-report.txt")
                 val detektion = createDetektion()
                 addData(detektion)
-                // Casting expectedContent to Any is workaround for
-                // https://github.com/joel-costigliola/assertj-core/issues/1440#issuecomment-465032464
-                assertThat(report.render(detektion)).isEqualTo(expectedContent as Any)
+                assertThat(report.render(detektion)).isEqualTo(expectedContent)
             }
 
             it("returns null for missing complexity metrics in report") {
@@ -41,6 +40,7 @@ private fun createDetektion(): Detektion = DetektResult(mapOf(Pair("Key", listOf
 
 private fun addData(detektion: Detektion) {
     detektion.addData(complexityKey, 2)
+    detektion.addData(CognitiveComplexity.KEY, 2)
     detektion.addData(linesKey, 10)
     detektion.addData(sourceLinesKey, 6)
     detektion.addData(logicalLinesKey, 5)

detekt-cli/src/test/kotlin/io/gitlab/arturbosch/detekt/cli/out/HtmlOutputReportSpec.kt

@@ -1,5 +1,6 @@
 package io.gitlab.arturbosch.detekt.cli.out
 
+import io.github.detekt.metrics.CognitiveComplexity
 import io.github.detekt.metrics.processors.commentLinesKey
 import io.github.detekt.metrics.processors.complexityKey
 import io.github.detekt.metrics.processors.linesKey
@@ -114,6 +115,7 @@ class HtmlOutputReportSpec : Spek({
         it("renders the complexity report correctly") {
             val detektion = TestDetektion()
             detektion.addData(complexityKey, 10)
+            detektion.addData(CognitiveComplexity.KEY, 10)
             detektion.addData(sourceLinesKey, 20)
             detektion.addData(logicalLinesKey, 10)
             detektion.addData(commentLinesKey, 2)

detekt-cli/src/test/resources/complexity-report.txt

@@ -3,7 +3,8 @@ Complexity Report:
 	- 6 source lines of code (sloc)
 	- 5 logical lines of code (lloc)
 	- 4 comment lines of code (cloc)
-	- 2 McCabe complexity (mcc)
+	- 2 cyclomatic complexity (mcc)
+	- 2 cognitive complexity
 	- 1 number of total code smells
 	- 66% comment source ratio
 	- 400 mcc per 1,000 lloc

detekt-metrics/src/main/kotlin/io/github/detekt/metrics/CognitiveComplexity.kt

@@ -1,6 +1,7 @@
 package io.github.detekt.metrics
 
 import io.gitlab.arturbosch.detekt.api.DetektVisitor
+import org.jetbrains.kotlin.com.intellij.openapi.util.Key
 import org.jetbrains.kotlin.com.intellij.psi.tree.IElementType
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.KtBinaryExpression
@@ -175,6 +176,8 @@ class CognitiveComplexity private constructor() : DetektVisitor() {
 
     companion object {
 
+        val KEY = Key<Int>("detekt.metrics.cognitive_complexity")
+
         private val logicalOps = setOf(KtTokens.ANDAND, KtTokens.OROR)
 
         fun calculate(element: KtElement): Int {

detekt-metrics/src/main/kotlin/io/github/detekt/metrics/processors/ProjectCognitiveComplexityProcessor.kt

@@ -0,0 +1,18 @@
+package io.github.detekt.metrics.processors
+
+import io.github.detekt.metrics.CognitiveComplexity
+import io.gitlab.arturbosch.detekt.api.DetektVisitor
+import org.jetbrains.kotlin.psi.KtFile
+
+class ProjectCognitiveComplexityProcessor : AbstractProcessor() {
+
+    override val visitor = object : DetektVisitor() {
+
+        override fun visitKtFile(file: KtFile) {
+            val complexity = CognitiveComplexity.calculate(file)
+            file.putUserData(CognitiveComplexity.KEY, complexity)
+        }
+    }
+
+    override val key = CognitiveComplexity.KEY
+}

detekt-metrics/src/test/kotlin/io/github/detekt/metrics/processors/CognitiveComplexityProcessorSpec.kt

@@ -0,0 +1,22 @@
+package io.github.detekt.metrics.processors
+
+import io.github.detekt.metrics.CognitiveComplexity
+import io.github.detekt.test.utils.compileContentForTest
+import org.assertj.core.api.Assertions.assertThat
+import org.spekframework.spek2.Spek
+import org.spekframework.spek2.style.specification.describe
+
+class CognitiveComplexityProcessorSpec : Spek({
+
+    describe("CognitiveComplexityProcessor") {
+
+        it("counts the complexity for the whole file") {
+            val file = compileContentForTest(complexClass)
+
+            val value = MetricProcessorTester(file)
+                .test(ProjectCognitiveComplexityProcessor(), CognitiveComplexity.KEY)
+
+            assertThat(value).isEqualTo(46)
+        }
+    }
+})

detekt-metrics/src/test/kotlin/io/github/detekt/metrics/processors/MetricProcessorTester.kt

@@ -0,0 +1,50 @@
+package io.github.detekt.metrics.processors
+
+import io.gitlab.arturbosch.detekt.api.Detektion
+import io.gitlab.arturbosch.detekt.api.Finding
+import io.gitlab.arturbosch.detekt.api.Notification
+import io.gitlab.arturbosch.detekt.api.ProjectMetric
+import io.gitlab.arturbosch.detekt.api.RuleSetId
+import org.jetbrains.kotlin.com.intellij.openapi.util.Key
+import org.jetbrains.kotlin.com.intellij.util.keyFMap.KeyFMap
+import org.jetbrains.kotlin.psi.KtFile
+
+class MetricProcessorTester(
+    private val file: KtFile,
+    private val result: Detektion = MetricResults()
+) {
+
+    fun <T : Any> test(processor: AbstractProcessor, key: Key<T>): T {
+        with(processor) {
+            onStart(listOf(file))
+            onProcess(file)
+            onProcessComplete(file, emptyMap())
+            onFinish(listOf(file), result)
+        }
+        return checkNotNull(result.getData(key))
+    }
+}
+
+private class MetricResults : Detektion {
+    override val findings: Map<RuleSetId, List<Finding>>
+        get() = throw UnsupportedOperationException()
+    override val notifications: Collection<Notification>
+        get() = throw UnsupportedOperationException()
+    override val metrics: MutableList<ProjectMetric> = mutableListOf()
+
+    private var data = KeyFMap.EMPTY_MAP
+
+    override fun <V> getData(key: Key<V>): V? = data.get(key)
+
+    override fun <V> addData(key: Key<V>, value: V) {
+        data = data.plus(key, value)
+    }
+
+    override fun add(notification: Notification) {
+        throw UnsupportedOperationException()
+    }
+
+    override fun add(projectMetric: ProjectMetric) {
+        metrics.add(projectMetric)
+    }
+}