Add when support for USELESS_IS_CHECK quick fix, related to KT-18965

idea/testData/quickfix/expressions/removeUselessIsCheckInWhen.kt

@@ -1,6 +1,11 @@
-// "Remove useless is check" "false"
-fun foo(a: String) {
-    when (1) {
-        <caret>is Int -> { }
+// "Remove useless is check" "true"
+interface Base
+interface Derived: Base
+
+fun foo(bar: Base):Int {
+    return when (bar) {
+        is Derived -> 0
+        <caret>is Base -> 42
+        else -> 1
     }
 }

idea/testData/quickfix/expressions/removeUselessIsCheckInWhen.kt.after

@@ -0,0 +1,10 @@
+// "Remove useless is check" "true"
+interface Base
+interface Derived: Base
+
+fun foo(bar: Base):Int {
+    return when (bar) {
+        is Derived -> 0
+        else -> 42
+    }
+}

idea/testData/quickfix/expressions/removeUselessIsCheckInWhenExpressionless.kt

@@ -0,0 +1,12 @@
+// "Remove useless is check" "true"
+
+interface Base
+interface Derived: Base
+
+fun foo(bar: Base):Int {
+    return when {
+        bar is Derived -> 0
+        bar <caret>is Base -> 42
+        else -> 1
+    }
+}

idea/testData/quickfix/expressions/removeUselessIsCheckInWhenExpressionless.kt.after

@@ -0,0 +1,12 @@
+// "Remove useless is check" "true"
+
+interface Base
+interface Derived: Base
+
+fun foo(bar: Base):Int {
+    return when {
+        bar is Derived -> 0
+        true -> 42
+        else -> 1
+    }
+}

idea/testData/quickfix/expressions/removeUselessIsCheckInWhenExpressionlessNegate.kt

@@ -0,0 +1,12 @@
+// "Remove useless is check" "true"
+
+interface Base
+interface Derived: Base
+
+fun foo(bar: Base):Int {
+    return when {
+        bar is Derived -> 0
+        bar <caret>!is Base -> 42
+        else -> 1
+    }
+}

idea/testData/quickfix/expressions/removeUselessIsCheckInWhenExpressionlessNegate.kt.after

@@ -0,0 +1,12 @@
+// "Remove useless is check" "true"
+
+interface Base
+interface Derived: Base
+
+fun foo(bar: Base):Int {
+    return when {
+        bar is Derived -> 0
+        false -> 42
+        else -> 1
+    }
+}

idea/testData/quickfix/expressions/removeUselessIsCheckInWhenNegate.kt

@@ -0,0 +1,11 @@
+// "Remove useless is check" "true"
+interface Base
+interface Derived: Base
+
+fun foo(bar: Base):Int {
+    return when (bar) {
+        is Derived -> 0
+        <caret>!is Base -> 42
+        else -> 1
+    }
+}

idea/testData/quickfix/expressions/removeUselessIsCheckInWhenNegate.kt.after

@@ -0,0 +1,10 @@
+// "Remove useless is check" "true"
+interface Base
+interface Derived: Base
+
+fun foo(bar: Base):Int {
+    return when (bar) {
+        is Derived -> 0
+        else -> 1
+    }
+}