Add tests

detekt-core/src/main/kotlin/io/gitlab/arturbosch/detekt/core/BindingContext.kt

@@ -25,8 +25,9 @@ internal fun generateBindingContext(
     }
 
     val messageCollector = DetektMessageCollector(
-        debugPrinter = debugPrinter,
         minSeverity = CompilerMessageSeverity.ERROR,
+        debugPrinter = debugPrinter,
+        warningPrinter = warningPrinter,
     )
 
     val analyzer = AnalyzerWithCompilerReport(
@@ -44,29 +45,33 @@ internal fun generateBindingContext(
         )
     }
 
-    if (messageCollector.messages > 0) {
-        warningPrinter(
-            "The BindingContext was created with ${messageCollector.messages} issues. " +
-                "Run detekt with --debug to see the error messages."
-        )
-    }
+    messageCollector.printIssuesCountIfAny()
 
     return analyzer.analysisResult.bindingContext
 }
 
-private class DetektMessageCollector(
-    private val debugPrinter: (() -> String) -> Unit,
+internal class DetektMessageCollector(
     private val minSeverity: CompilerMessageSeverity,
+    private val debugPrinter: (() -> String) -> Unit,
+    private val warningPrinter: (String) -> Unit,
 ) : MessageCollector by MessageCollector.NONE {
-    var messages = 0
-        private set
+    private var messages = 0
 
     override fun report(severity: CompilerMessageSeverity, message: String, location: CompilerMessageSourceLocation?) {
         if (severity.ordinal <= minSeverity.ordinal) {
             debugPrinter { DetektMessageRenderer.render(severity, message, location) }
             messages++
         }
     }
+
+    fun printIssuesCountIfAny() {
+        if (messages > 0) {
+            warningPrinter(
+                "The BindingContext was created with $messages issues. " +
+                    "Run detekt with --debug to see the error messages."
+            )
+        }
+    }
 }
 
 private object DetektMessageRenderer : PlainTextMessageRenderer() {

detekt-core/src/test/kotlin/io/gitlab/arturbosch/detekt/core/DetektMessageCollectorSpec.kt

@@ -0,0 +1,88 @@
+package io.gitlab.arturbosch.detekt.core
+
+import io.mockk.Called
+import io.mockk.every
+import io.mockk.mockk
+import io.mockk.slot
+import io.mockk.verify
+import org.assertj.core.api.Assertions.assertThat
+import org.jetbrains.kotlin.cli.common.messages.CompilerMessageSeverity
+import org.spekframework.spek2.Spek
+import org.spekframework.spek2.lifecycle.CachingMode
+import org.spekframework.spek2.style.specification.describe
+
+internal object DetektMessageCollectorSpec : Spek({
+    describe("DetektMessageCollector") {
+        val debugPrinter: (() -> String) -> Unit by memoized(CachingMode.TEST) {
+            mockk {
+                every { this@mockk.invoke(any()) } returns Unit
+            }
+        }
+        val warningPrinter: (String) -> Unit by memoized(CachingMode.TEST) {
+            mockk {
+                every { this@mockk.invoke(any()) } returns Unit
+            }
+        }
+        val subject by memoized(CachingMode.TEST) {
+            DetektMessageCollector(
+                minSeverity = CompilerMessageSeverity.INFO,
+                debugPrinter = debugPrinter,
+                warningPrinter = warningPrinter,
+            )
+        }
+
+        describe("message with min severity") {
+            beforeEachTest { subject.report(CompilerMessageSeverity.INFO, "message", null) }
+
+            it("prints the message") {
+                val slot = slot<() -> String>()
+                verify { debugPrinter.invoke(capture(slot)) }
+                assertThat(slot.captured() == "info: message")
+            }
+
+            it("adds up to the message count") {
+                subject.printIssuesCountIfAny()
+
+                verify {
+                    warningPrinter(
+                        "The BindingContext was created with 1 issues. " +
+                            "Run detekt with --debug to see the error messages."
+                    )
+                }
+            }
+        }
+        describe("message with higher severity than the min severity") {
+            beforeEachTest { subject.report(CompilerMessageSeverity.WARNING, "message", null) }
+
+            it("prints the message") {
+                val slot = slot<() -> String>()
+                verify { debugPrinter.invoke(capture(slot)) }
+                assertThat(slot.captured() == "warning: message")
+            }
+
+            it("adds up to the message count") {
+                subject.printIssuesCountIfAny()
+
+                verify {
+                    warningPrinter(
+                        "The BindingContext was created with 1 issues. " +
+                            "Run detekt with --debug to see the error messages."
+                    )
+                }
+            }
+        }
+        describe("message with lower severity than the min severity") {
+            beforeEachTest { subject.report(CompilerMessageSeverity.LOGGING, "message", null) }
+
+            it("ignores the message") {
+                verify { debugPrinter wasNot Called }
+            }
+
+            it("doesn't add up to the message count") {
+                subject.printIssuesCountIfAny()
+
+                verify { warningPrinter wasNot Called }
+            }
+        }
+    }
+})