SONARKT-301 - Implement rule S6524: collection should be immutable (#390)

Author: erwan-serandour

kotlin-checks-test-sources/src/main/kotlin/checks/CollectionShouldBeImmutableCheckSample.kt

@@ -0,0 +1,228 @@
+package checks
+
+class CollectionShouldBeImmutableCheckSample {
+    fun MutableCollection<Int>.doSomething(): Unit {} // Noncompliant
+
+    //let also apply run with
+    fun nonCompliant(
+        x: MutableList<Int>, // Noncompliant {{Make this collection immutable.}}
+        y: MutableSet<String>,  // Noncompliant
+//      ^^^^^^^^^^^^^^^^^^^^^
+        z: MutableMap<Int, Int>, // Noncompliant
+        a: MutableList<Int>,  // compliant, FN
+        b: MutableList<Int>, // Noncompliant
+        c: MutableList<Int>, // compliant, FN
+    ): Unit {
+        baz(x.toList().toMutableList())
+        baz(doNothing(x).toMutableList())
+        doNothing(x)
+        x.reduce { acc, it -> acc + it }
+        x + 1
+        x.size
+        for (i in x) {
+            println(i)
+        }
+        x.foo()
+        id(x + listOf(1, 2, 3))
+        y.contains("a")
+        y.map { it + "a" }
+        z[1]
+        doNothing(x, y, z)
+        a.let { it.size }
+        a.let { it.also { with(it, { this.size }) } }
+        Pair(1, b.reduce { acc, i -> i + acc })
+        id(c)
+    }
+
+    fun List<Int>.toList(): List<Int> = this // compliant
+    fun baz(list : MutableList<Int>): Unit {} // Noncompliant
+
+    fun List<Int>.foo(): Unit {} // Compliant
+    fun doNothing(a : List<Int>, b : Set<String>, c : Map<Int,Int>): Unit {}
+    fun doNothing(a : List<Int>): List<Int> { return a } // Compliant
+
+    fun <A>id(a : A): A = a // Compliant
+
+    fun compliantScopedFunctions(
+        a: MutableList<Int>, // Compliant
+        b: MutableList<Int>, // Compliant
+        c: MutableList<Int>, // Compliant
+        d: MutableList<Int>, // Compliant
+        e: MutableList<Int>, // Compliant
+        f: MutableList<Int>, // Compliant
+        crazy: MutableList<Int>,
+    ): Unit { // Compliant
+        a.let { it.add(1) }
+        b.also { it.add(1) }
+        c.apply { add(1) }
+        d.run { add(1) }
+        with(e) { add(1) }
+        f.let { it.let { it.let { it.add(1) } } }
+        crazy.let { it.also { it.apply { it.run { with(this) { it.add(1) } } } } }
+    }
+
+    fun MutableList<Int>.doSomething2(): MutableList<Int> { return this } // Noncompliant
+
+    fun compliantFunctionsCalledOn(
+        a: MutableList<Int>, // Compliant
+        b: MutableList<Int>, // Compliant
+        c: List<Int>, // Compliant
+        d: MutableList<Int>, // Compliant
+        e: MutableMap<Int, Int>, // Compliant
+        f: MutableList<Int>, // Compliant
+        g: MutableList<Int>, // Compliant
+        h: MutableSet<Int>, // Compliant
+        i: MutableList<Int>, // Compliant
+        j: MutableList<Int>, // Compliant
+        k: MutableList<Int>, // Compliant
+        l: MutableList<Int>, // Compliant
+        m: MutableList<Int>, // Compliant
+        n: MutableList<Int>, // Compliant
+    ): Unit {
+        a.add(1)
+        b.iterator()
+        c.map { it + 1}
+        d.add(1)
+        e.remove(1)
+        f.doSomething()
+        g.doSomething2()
+        h.doSomething()
+        ((i)).doSomething()
+        j.doSomething2().doSomething2().doSomething2()
+        when (k) {
+            is MutableList<Int> -> k.doSomething()
+        }
+        l!!.doSomething()
+        m?.doSomething()
+        if(true){n}else{n}.doSomething()
+    }
+
+
+    fun compliantBinaryExprCalledOn(
+        c: List<Int>, // Compliant
+        d: MutableList<Int>, // Compliant
+        e: MutableList<Int>, // Compliant
+        f: MutableList<Int>, // Compliant
+        g: MutableList<Int>, // Compliant
+    ): Unit {
+        c[0]
+        d += 1
+        e -= 1
+        f[0] = 1
+        (g)[0] = 1
+    }
+
+
+
+    fun compliantCalledInFun(
+        a: MutableList<Int>, // Compliant
+        b: MutableList<Int>, // Compliant
+        c: MutableList<Int>, // Compliant
+        d: MutableList<Int>, // Compliant
+        e: MutableList<Int>, // Compliant
+        f: MutableList<Int> // Compliant
+    ): Unit {
+        foo_(a)
+        foo2(b)
+        foo_(((c)))
+        foo_(d!!)
+        foo_(if(true){e}else{e})
+        Pair(f, 1)
+    }
+
+    fun foo_(x : MutableList<Int>): Unit {} // Noncompliant {{Make this collection immutable.}}
+    fun foo2(x : MutableCollection<Int>): Unit {} // Noncompliant
+
+
+    fun nonCompliantParameter(list: MutableList<Int>): Int { // Noncompliant
+        return list.reduce { acc, it -> acc + it}
+    }
+
+    fun compliantParameter(list: List<Int>): Int { // Compliant
+        return list.reduce { acc, it -> acc + it}
+    }
+
+    fun MutableList<Int>.compliantDelegate(): Int { // Compliant
+        this.add(1)
+        return reduce { acc, it -> acc + it }
+    }
+
+
+    fun MutableList<Int>.compliantDelegate2(): Unit { // Compliant
+        foo_(this)
+    }
+
+    fun MutableList<Int>.compliantDelegate3(): Unit { // Compliant
+        foo_(this)
+        add(1)
+    }
+
+    fun MutableList<Int>.compliantDelegate4(): Unit { // Compliant
+        if(add(1)) {}
+    }
+
+    fun MutableList<Int>.noncompliantDelegate(): Int { // Noncompliant
+//      ^^^^^^^^^^^^^^^^
+        return reduce { acc, it -> acc + it}
+    }
+
+    fun MutableList<Int>.noncompliantDelegate2(): Int { // compliant, FN
+        var list = mutableListOf(1, 2, 3) // we should change noReciever to check that it is called on this
+        list.add(1)
+        return reduce { acc, it -> acc + it}
+    }
+
+
+
+    class AMutableCollections : MutableCollection<Int> {
+        override val size: Int
+            get() = TODO()
+
+        override fun contains(element: Int): Boolean {
+            TODO()
+        }
+
+        override fun containsAll(elements: Collection<Int>): Boolean {
+            TODO()
+        }
+
+        override fun isEmpty(): Boolean {
+            TODO()
+        }
+
+        override fun add(element: Int): Boolean {
+            TODO()
+        }
+
+        override fun addAll(elements: Collection<Int>): Boolean {
+            TODO()
+        }
+
+        override fun clear() {
+            TODO()
+        }
+
+        override fun iterator(): MutableIterator<Int> {
+            TODO()
+        }
+
+        override fun remove(element: Int): Boolean {
+            TODO()
+        }
+
+        override fun removeAll(elements: Collection<Int>): Boolean {
+            TODO()
+        }
+
+        override fun retainAll(elements: Collection<Int>): Boolean {
+            TODO()
+        }
+    }
+
+    fun id(x : AMutableCollections): AMutableCollections = x // compliant, for now don't know how to check that is subtype of MutableCollection
+
+
+    fun foo(configure: (MutableMap<String, Any?>) -> Unit): Unit { // compliant
+    }
+
+}