MultilineLambdaItParameter: fix false positive for one-line statement…

…s with a lambda argument (#5505)
detekt · Nov 5, 2022 · 9306a27 · 9306a27
1 parent 9b38f67
commit 9306a27
Show file tree

Hide file tree

Showing 2 changed files with 44 additions and 4 deletions.
diff --git a/...yle/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/MultilineLambdaItParameter.kt b/...yle/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/style/MultilineLambdaItParameter.kt
@@ -12,8 +12,10 @@ import io.gitlab.arturbosch.detekt.rules.IT_LITERAL
 import io.gitlab.arturbosch.detekt.rules.hasImplicitParameterReference
 import io.gitlab.arturbosch.detekt.rules.implicitParameter
 import org.jetbrains.kotlin.psi.KtBlockExpression
+import org.jetbrains.kotlin.psi.KtExpression
 import org.jetbrains.kotlin.psi.KtLambdaExpression
-import org.jetbrains.kotlin.psi.psiUtil.collectDescendantsOfType
+import org.jetbrains.kotlin.psi.psiUtil.anyDescendantOfType
+import org.jetbrains.kotlin.utils.ifEmpty
 
 /**
  * Lambda expressions are very useful in a lot of cases, and they often include very small chunks of
@@ -76,8 +78,10 @@ class MultilineLambdaItParameter(val config: Config) : Rule(config) {
 
     override fun visitLambdaExpression(lambdaExpression: KtLambdaExpression) {
         super.visitLambdaExpression(lambdaExpression)
-        val size = lambdaExpression.collectDescendantsOfType<KtBlockExpression>().sumOf { it.statements.size }
-        if (size <= 1) return
+
+        val statements = lambdaExpression.bodyExpression?.statements.orEmpty().ifEmpty { return }
+        val single = statements.singleOrNull()
+        if (single != null && (single.hasNoLineBreak() || single.hasNoStatements())) return
 
         val parameterNames = lambdaExpression.valueParameters.map { it.name }
         // Explicit `it`
@@ -106,4 +110,9 @@ class MultilineLambdaItParameter(val config: Config) : Rule(config) {
             }
         }
     }
+
+    private fun KtExpression.hasNoLineBreak() = !textContains('\n')
+
+    private fun KtExpression.hasNoStatements() =
+        !anyDescendantOfType<KtBlockExpression> { it.statements.isNotEmpty() }
 }
diff --git a/...src/test/kotlin/io/gitlab/arturbosch/detekt/rules/style/MultilineLambdaItParameterSpec.kt b/...src/test/kotlin/io/gitlab/arturbosch/detekt/rules/style/MultilineLambdaItParameterSpec.kt
@@ -121,14 +121,32 @@ class MultilineLambdaItParameterSpec(val env: KotlinCoreEnvironment) {
             fun f() {
                 val digits = 1234.let {
                     check(it > 0) {
-                        println(it)
+                        println("error")
                     }
                 }
             }
             """.trimIndent()
             val findings = subject.compileAndLintWithContext(env, code)
             assertThat(findings).hasSize(1)
         }
+
+        @Test
+        fun `does not report when statement has no nested statements`() {
+            val code = """
+            data class Foo(val x: Int, val y: Int)
+            
+            fun f(i: Int?) {
+                val foo = i?.let {
+                    Foo(
+                        x = it,
+                        y = 2
+                    )
+                }
+            }
+            """.trimIndent()
+            val findings = subject.compileAndLintWithContext(env, code)
+            assertThat(findings).isEmpty()
+        }
     }
 
     @Nested
@@ -171,6 +189,19 @@ class MultilineLambdaItParameterSpec(val env: KotlinCoreEnvironment) {
             val code = """
             fun f() {
                 val digits = 1234.let { param -> listOf(param) }
+            }   
+            """.trimIndent()
+            val findings = subject.compileAndLintWithContext(env, code)
+            assertThat(findings).isEmpty()
+        }
+
+        @Test
+        fun `does not report when statement has one-line lambda argument`() {
+            val code = """
+            fun f() {
+                val digits = 1234.let {
+                    check(it > 0) { println("error") }
+                }
             }
             """.trimIndent()
             val findings = subject.compileAndLintWithContext(env, code)