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UnnecessaryFilterSpec.kt
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UnnecessaryFilterSpec.kt
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package io.gitlab.arturbosch.detekt.rules.style
import io.gitlab.arturbosch.detekt.rules.KotlinCoreEnvironmentTest
import io.gitlab.arturbosch.detekt.test.assertThat
import io.gitlab.arturbosch.detekt.test.compileAndLintWithContext
import org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment
import org.junit.jupiter.api.DisplayName
import org.junit.jupiter.api.Nested
import org.junit.jupiter.api.Test
@KotlinCoreEnvironmentTest
class UnnecessaryFilterSpec(val env: KotlinCoreEnvironment) {
val subject = UnnecessaryFilter()
@Nested
inner class UnnecessaryFilterTest {
@Test
fun `Filter with size`() {
val code = """
val x = listOf(1, 2, 3)
.filter { it > 1 }
.size
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).hasSize(1)
assertThat(findings[0]).hasMessage("'filter { it > 1 }' can be replaced by 'count { it > 1 }'")
}
@Test
fun `Filter with count`() {
val code = """
val x = listOf(1, 2, 3)
.filter { it > 1 }
.count()
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).hasSize(1)
}
@Test
fun `Sequence with count`() {
val code = """
val x = listOf(1, 2, 3)
.asSequence()
.map { it * 2 }
.filter { it > 1 }
.count()
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).hasSize(1)
}
@Test
fun `None item`() {
val code = """
val x = listOf(1, 2, 3)
.filter { it > 2 }
.isEmpty()
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).hasSize(1)
}
@Test
fun `Any item`() {
val code = """
val x = listOf(1, 2, 3)
.filter { it > 2 }
.isNotEmpty()
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).hasSize(1)
}
}
@Nested
inner class `Correct filter` {
@Test
fun `Not stdlib count list function`() {
val code = """
fun <T> List<T>.count() : Any{
return Any()
}
val x = listOf<Int>().count()
val y = listOf<Int>().filter { it > 0 }.count()
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).isEmpty()
}
@Test
fun `Not stdlib count sequences function`() {
val code = """
fun <T> Sequence<T>.count() : Any{
return Any()
}
val x = listOf<Int>().asSequence().count()
val y = listOf<Int>().asSequence().filter { it > 0 }.count()
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).isEmpty()
}
@Test
fun `Not stdlib filter function`() {
val code = """
fun filter() : List<Any>{
return emptyList()
}
val x = filter().size
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).isEmpty()
}
@Test
fun `Filter with count`() {
val code = """
val x = listOf(1, 2, 3)
.count { it > 2 }
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).isEmpty()
}
@Test
fun `None item`() {
val code = """
val x = listOf(1, 2, 3)
.none { it > 2 }
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).isEmpty()
}
@Test
fun `Any item`() {
val code = """
val x = listOf(1, 2, 3)
.any { it > 2 }
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).isEmpty()
}
@Test
fun `Sequence with count`() {
val code = """
val x = listOf(1, 2, 3)
.asSequence()
.map { it * 2 }
.count { it > 1 }
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).isEmpty()
}
// https://github.com/detekt/detekt/issues/3541#issuecomment-815136831
@Test
fun `Size in another statement`() {
val code = """
fun foo() {
val strings = listOf("abc", "cde", "ader")
val filteredStrings = strings.filter { "a" in it }
filteredStrings.forEach { println(it) }
if (filteredStrings.size > 2) {
println("more than two")
}
}
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).isEmpty()
}
// https://github.com/detekt/detekt/issues/3541
@Test
@DisplayName("Size/isEmpty()/isNotEmpty() in another statement")
fun filterUsedInOtherStatement() {
val code = """
fun test(queryParts: List<String>, a: List<String>, b: List<String>, c: List<String>) {
val dbQueryParts = queryParts.filter { it.length > 1 }.take(3)
a.size
b.isEmpty()
c.isNotEmpty()
}
"""
val findings = subject.compileAndLintWithContext(env, code)
assertThat(findings).isEmpty()
}
}
}