Lift assignment: suggest for assignment of null

#KT-30191 Fixed
 #KT-28595 Fixed

idea/testData/inspectionsLocal/liftOut/ifToAssignment/hasNull.kt

@@ -0,0 +1,11 @@
+fun bar(i: Int) {
+    var str: String? = null
+
+    <caret>if (i == 1) {
+        str = null
+    } else if (i == 2) {
+        str = "2"
+    } else {
+        str = "3"
+    }
+}

idea/testData/inspectionsLocal/liftOut/ifToAssignment/hasNull.kt.after

@@ -0,0 +1,11 @@
+fun bar(i: Int) {
+    var str: String? = null
+
+    str = if (i == 1) {
+        null
+    } else if (i == 2) {
+        "2"
+    } else {
+        "3"
+    }
+}

idea/testData/inspectionsLocal/liftOut/ifToAssignment/hasNull2.kt

@@ -0,0 +1,11 @@
+fun bar(i: Int) {
+    var str: String? = null
+
+    <caret>if (i == 1) {
+        str = "1"
+    } else if (i == 2) {
+        str = "2"
+    } else {
+        str = null
+    }
+}

idea/testData/inspectionsLocal/liftOut/ifToAssignment/hasNull2.kt.after

@@ -0,0 +1,11 @@
+fun bar(i: Int) {
+    var str: String? = null
+
+    str = if (i == 1) {
+        "1"
+    } else if (i == 2) {
+        "2"
+    } else {
+        null
+    }
+}

idea/testData/inspectionsLocal/liftOut/ifToAssignment/hasNull3.kt

@@ -0,0 +1,11 @@
+fun bar(i: Int) {
+    var str: String? = null
+
+    <caret>if (i == 1) {
+        str = null
+    } else if (i == 2) {
+        str = null
+    } else {
+        str = null
+    }
+}

idea/testData/inspectionsLocal/liftOut/ifToAssignment/hasNull3.kt.after

@@ -0,0 +1,11 @@
+fun bar(i: Int) {
+    var str: String? = null
+
+    str = if (i == 1) {
+        null
+    } else if (i == 2) {
+        null
+    } else {
+        null
+    }
+}

idea/testData/inspectionsLocal/liftOut/ifToAssignment/hasNull4.kt

@@ -0,0 +1,13 @@
+// PROBLEM: none
+// DISABLE-ERRORS
+fun bar(i: Int) {
+    var str: String? = null
+
+    <caret>if (i == 1) {
+        str = null
+    } else if (i == 2) {
+        str = "2"
+    } else {
+        str = 3
+    }
+}

idea/testData/inspectionsLocal/liftOut/ifToAssignment/hasNull5.kt

@@ -0,0 +1,13 @@
+// PROBLEM: none
+// DISABLE-ERRORS
+fun bar(i: Int) {
+    var str: String = ""
+
+    <caret>if (i == 1) {
+        str = null
+    } else if (i == 2) {
+        str = "2"
+    } else {
+        str = "3"
+    }
+}

idea/testData/inspectionsLocal/liftOut/ifToAssignment/subTypes.kt

@@ -0,0 +1,12 @@
+open class A
+class B : A()
+class C : A()
+
+fun liftClass(boolean: Boolean) {
+    val a1: A
+    <caret>if (boolean) {
+        a1 = B()
+    } else {
+        a1 = C()
+    }
+}

idea/testData/inspectionsLocal/liftOut/ifToAssignment/subTypes.kt.after

@@ -0,0 +1,12 @@
+open class A
+class B : A()
+class C : A()
+
+fun liftClass(boolean: Boolean) {
+    val a1: A
+    a1 = if (boolean) {
+        B()
+    } else {
+        C()
+    }
+}