Testing and rule improvement for EmptyElseBlock

detekt-rules-empty/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/empty/EmptyElseBlock.kt

@@ -1,6 +1,8 @@
 package io.gitlab.arturbosch.detekt.rules.empty
 
+import io.gitlab.arturbosch.detekt.api.CodeSmell
 import io.gitlab.arturbosch.detekt.api.Config
+import io.gitlab.arturbosch.detekt.api.Entity
 import io.gitlab.arturbosch.detekt.api.internal.ActiveByDefault
 import org.jetbrains.kotlin.psi.KtIfExpression
 
@@ -9,9 +11,16 @@ import org.jetbrains.kotlin.psi.KtIfExpression
  */
 @ActiveByDefault(since = "1.0.0")
 class EmptyElseBlock(config: Config) : EmptyRule(config) {
-
     override fun visitIfExpression(expression: KtIfExpression) {
         super.visitIfExpression(expression)
-        expression.`else`?.addFindingIfBlockExprIsEmpty()
+        expression.`else`?.addFindingIfBlockExprIsEmpty() ?: checkThenBodyForLoneSemicolon(expression) {
+            report(
+                CodeSmell(
+                    issue,
+                    Entity.from(it),
+                    "This else block is empty and can be removed."
+                )
+            )
+        }
     }
 }

detekt-rules-empty/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/empty/EmptyIfBlock.kt

@@ -4,25 +4,23 @@ import io.gitlab.arturbosch.detekt.api.CodeSmell
 import io.gitlab.arturbosch.detekt.api.Config
 import io.gitlab.arturbosch.detekt.api.Entity
 import io.gitlab.arturbosch.detekt.api.internal.ActiveByDefault
-import org.jetbrains.kotlin.com.intellij.psi.impl.source.tree.LeafPsiElement
-import org.jetbrains.kotlin.lexer.KtSingleValueToken
 import org.jetbrains.kotlin.psi.KtIfExpression
 
 /**
  * Reports empty `if` blocks. Empty blocks of code serve no purpose and should be removed.
  */
 @ActiveByDefault(since = "1.0.0")
 class EmptyIfBlock(config: Config) : EmptyRule(config) {
-
     override fun visitIfExpression(expression: KtIfExpression) {
         super.visitIfExpression(expression)
-        expression.then?.addFindingIfBlockExprIsEmpty() ?: checkThenBodyForLoneSemicolon(expression)
-    }
-
-    private fun checkThenBodyForLoneSemicolon(expression: KtIfExpression) {
-        val valueOfNextSibling = (expression.nextSibling as? LeafPsiElement)?.elementType as? KtSingleValueToken
-        if (valueOfNextSibling?.value?.trim() == ";") {
-            report(CodeSmell(issue, Entity.from(expression), "This if block is empty and can be removed."))
+        expression.then?.addFindingIfBlockExprIsEmpty() ?: checkThenBodyForLoneSemicolon(expression) {
+            report(
+                CodeSmell(
+                    issue,
+                    Entity.from(it),
+                    "This if block is empty and can be removed."
+                )
+            )
         }
     }
 }

detekt-rules-empty/src/main/kotlin/io/gitlab/arturbosch/detekt/rules/empty/EmptyRule.kt

@@ -8,8 +8,11 @@ import io.gitlab.arturbosch.detekt.api.Issue
 import io.gitlab.arturbosch.detekt.api.Rule
 import io.gitlab.arturbosch.detekt.api.Severity
 import io.gitlab.arturbosch.detekt.rules.hasCommentInside
+import org.jetbrains.kotlin.com.intellij.psi.impl.source.tree.LeafPsiElement
+import org.jetbrains.kotlin.lexer.KtSingleValueToken
 import org.jetbrains.kotlin.psi.KtBlockExpression
 import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.kotlin.psi.KtIfExpression
 
 /**
  * Rule to detect empty blocks of code.
@@ -36,6 +39,13 @@ abstract class EmptyRule(
         checkBlockExpr(true)
     }
 
+    protected fun checkThenBodyForLoneSemicolon(expression: KtIfExpression, reportBlock: (KtIfExpression) -> Unit) {
+        val valueOfNextSibling = (expression.nextSibling as? LeafPsiElement)?.elementType as? KtSingleValueToken
+        if (valueOfNextSibling?.value?.trim() == ";") {
+            reportBlock(expression)
+        }
+    }
+
     private fun KtExpression.checkBlockExpr(skipIfCommented: Boolean = false) {
         if (this !is KtBlockExpression) return
         val hasComment = hasCommentInside()

detekt-rules-empty/src/test/kotlin/io/gitlab/arturbosch/detekt/rules/empty/EmptyElseBlockSpec.kt

@@ -0,0 +1,105 @@
+package io.gitlab.arturbosch.detekt.rules.empty
+
+import io.gitlab.arturbosch.detekt.api.Config
+import io.gitlab.arturbosch.detekt.test.compileAndLint
+import org.assertj.core.api.Assertions
+import org.spekframework.spek2.Spek
+import org.spekframework.spek2.style.specification.describe
+
+class EmptyElseBlockSpec : Spek({
+
+    val subject by memoized { EmptyElseBlock(Config.empty) }
+
+    describe("EmptyElseBlock rule") {
+        it("reports empty else block") {
+            val code = """
+                fun f() {
+                    val i = 0
+                    if (i == 0) {
+                        println(i)
+                    } else {
+
+                    }
+                }
+            """
+            Assertions.assertThat(subject.compileAndLint(code)).hasSize(1)
+        }
+
+        it("reports empty else blocks with trailing semicolon") {
+            val code = """
+                fun f() {
+                    val i = 0
+                    if (i == 0) {
+                        println(i)
+                    } else ;
+                }
+            """
+            Assertions.assertThat(subject.compileAndLint(code)).hasSize(1)
+        }
+        it("reports empty else with trailing semicolon on new line") {
+            val code = """
+                fun f() {
+                    var i = 0
+                    if (i == 0) {
+                        println(i)
+                    } else
+                    ;
+                    i++
+                }
+            """
+            Assertions.assertThat(subject.compileAndLint(code)).hasSize(1)
+        }
+
+        it("reports empty else with trailing semicolon and braces") {
+            val code = """
+                fun f() {
+                    var i = 0
+                    if (i == 0) {
+                        println()
+                    } else; {
+                    }
+                    i++
+                }
+            """
+            Assertions.assertThat(subject.compileAndLint(code)).hasSize(1)
+        }
+
+        it("does not report nonempty else with braces") {
+            val code = """
+                fun f() {
+                    var i = 0
+                    if (i == 0) {
+                        println(i)
+                    } else {
+                        i++
+                    }
+                }
+            """
+            Assertions.assertThat(subject.compileAndLint(code)).isEmpty()
+        }
+
+        it("does not report nonempty else without braces") {
+            val code = """
+                fun f() {
+                    var i = 0
+                    if (i == 0) {
+                        println(i)
+                    } else i++
+                }
+            """
+            Assertions.assertThat(subject.compileAndLint(code)).isEmpty()
+        }
+
+        it("does not report nonempty else without braces but semicolon") {
+            val code = """
+                fun f() {
+                    var i = 0
+                    if (i == 0) {
+                        println(i)
+                    } else i++;
+                }
+            """
+            Assertions.assertThat(subject.compileAndLint(code)).isEmpty()
+        }
+    }
+})