From 85533a0dbd0e316a9cc27b76a8b29aefa3754e6f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Paz?= <andre.paz@gmail.com>
Date: Sat, 19 Jun 2021 08:29:24 -0300
Subject: [PATCH] Improve LongParameterList rule by supporting ignoring
 annotated parameters (#3879)

---
 README.md                                     |  1 +
 .../rules/complexity/LongParameterList.kt     | 12 ++++---
 .../rules/complexity/LongParameterListSpec.kt | 35 ++++++++++++++++++-
 3 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 0f8d5cfec..66b68478e 100644
--- a/README.md
+++ b/README.md
@@ -222,6 +222,7 @@ If you contributed to detekt but your name is not in the list, please feel free
 - [Vinicius Montes Munhoz](https://github.com/vfmunhoz) - Documentation improvement
 - [Eliezer Graber](https://github.com/eygraber) - Rule fix: ModifierOrder
 - [Dominik Labuda](https://github.com/Dominick1993) - Gradle plugin improvement
+- [Andre Paz](https://github.com/andrepaz) - Rule improvement: LongParameterList
 
 ### Mentions
 
diff --git a/detekt-rules-complexity/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/complexity/LongParameterList.kt b/detekt-rules-complexity/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/complexity/LongParameterList.kt
index 5c49f22d6..17ba7c971 100644
--- a/detekt-rules-complexity/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/complexity/LongParameterList.kt
+++ b/detekt-rules-complexity/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/complexity/LongParameterList.kt
@@ -63,9 +63,10 @@ class LongParameterList(config: Config = Config.empty) : Rule(config) {
     private val ignoreDataClasses: Boolean by config(defaultValue = true)
 
     @Configuration(
-        "ignore long parameters list for constructors or functions in the " +
-            "context of these annotation class names; (e.g. ['Inject', 'Module', 'Suppress']); " +
-            "the most common case is for dependency injection where constructors are annotated with `@Inject`."
+        "ignore long parameters list for constructors, functions or their parameters in the " +
+            "context of these annotation class names; (e.g. ['Inject', 'Module', 'Suppress', 'Value']); " +
+            "the most common cases are for dependency injection where constructors are annotated with `@Inject` " +
+            "or parameters are annotated with `@Value` and should not be counted for the rule to trigger"
     )
     private val ignoreAnnotated: List<String> by config(listOf<String>()) { list ->
         list.map { it.removePrefix("*").removeSuffix("*") }
@@ -131,10 +132,11 @@ class LongParameterList(config: Config = Config.empty) : Rule(config) {
     }
 
     private fun KtParameterList.parameterCount(): Int {
+        val preFilteredParameters = parameters.filter { !it.isIgnored() }
         return if (ignoreDefaultParameters) {
-            parameters.filter { !it.hasDefaultValue() }.size
+            preFilteredParameters.filter { !it.hasDefaultValue() }.size
         } else {
-            parameters.size
+            preFilteredParameters.size
         }
     }
 
diff --git a/detekt-rules-complexity/src/test/kotlin/io/gitlab/arturbosch/detekt/rules/complexity/LongParameterListSpec.kt b/detekt-rules-complexity/src/test/kotlin/io/gitlab/arturbosch/detekt/rules/complexity/LongParameterListSpec.kt
index 46edf06ca..413fae36d 100644
--- a/detekt-rules-complexity/src/test/kotlin/io/gitlab/arturbosch/detekt/rules/complexity/LongParameterListSpec.kt
+++ b/detekt-rules-complexity/src/test/kotlin/io/gitlab/arturbosch/detekt/rules/complexity/LongParameterListSpec.kt
@@ -102,7 +102,8 @@ class LongParameterListSpec : Spek({
                         "ignoreAnnotated" to listOf(
                             "Generated",
                             "kotlin.Deprecated",
-                            "kotlin.jvm.JvmName"
+                            "kotlin.jvm.JvmName",
+                            "kotlin.Suppress"
                         ),
                         "functionThreshold" to 1,
                         "constructorThreshold" to 1
@@ -159,6 +160,38 @@ class LongParameterListSpec : Spek({
                 """
                 assertThat(rule.compileAndLint(code)).isEmpty()
             }
+
+            it("reports long parameter list for constructors if constructor parameters are annotated with annotation that is not ignored") {
+                val code = """
+                    @Target(AnnotationTarget.VALUE_PARAMETER)
+                    annotation class CustomAnnotation
+
+                    class Data constructor(@CustomAnnotation val a: Int)
+                """
+                assertThat(rule.compileAndLint(code)).hasSize(1)
+            }
+
+            it("reports long parameter list for functions if enough function parameters are annotated with annotation that is not ignored") {
+                val code = """
+                    @Target(AnnotationTarget.VALUE_PARAMETER)
+                    annotation class CustomAnnotation
+
+                    class Data { fun foo(@CustomAnnotation a: Int) {} }
+                """
+                assertThat(rule.compileAndLint(code)).hasSize(1)
+            }
+
+            it("does not report long parameter list for constructors if enough constructor parameters are annotated with ignored annotation") {
+                val code = "class Data constructor(@kotlin.Suppress(\"\") val a: Int)"
+                assertThat(rule.compileAndLint(code)).isEmpty()
+            }
+
+            it("does not report long parameter list for functions if enough function parameters are annotated with ignored annotation") {
+                val code = """class Data {
+                    fun foo(@kotlin.Suppress("") a: Int) {} }
+                """
+                assertThat(rule.compileAndLint(code)).isEmpty()
+            }
         }
     }
 })