ConvertSwitchToIfIntention: fixes after review IDEA-CR-37311:

1. Do not suggest intention if `default` case is not the last one and fallthrough is possible into or out of that case
2. Generate a code-block if side-effect should be extracted to variable

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/convertSwitchToIf/afterDeclareNoOuterBlock.java

@@ -0,0 +1,15 @@
+// "Replace 'switch' with 'if'" "true"
+class X {
+  int m(int i) {
+    if (i > 0) {
+        int i1 = ++i;
+        if (i1 == 1) {
+            System.out.println(1);
+
+            System.out.println(2);
+        } else if (i1 == 2) {
+            System.out.println(2);
+        }
+    }
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/convertSwitchToIf/afterDefaultMiddle.java

@@ -0,0 +1,12 @@
+// "Replace 'switch' with 'if'" "true"
+class X {
+  void m(String s) {
+      if ("foo".equals(s)) {
+          System.out.println(1);
+      } else if ("bar".equals(s)) {
+          System.out.println(3);
+      } else {
+          System.out.println(2);
+      }
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/convertSwitchToIf/beforeDeclareNoOuterBlock.java

@@ -0,0 +1,12 @@
+// "Replace 'switch' with 'if'" "true"
+class X {
+  int m(int i) {
+    if (i > 0)
+      sw<caret>itch (++i) {
+        case 1:
+          System.out.println(1);
+        case 2:
+          System.out.println(2);
+      }
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/convertSwitchToIf/beforeDefaultMiddle.java

@@ -0,0 +1,15 @@
+// "Replace 'switch' with 'if'" "true"
+class X {
+  void m(String s) {
+    swi<caret>tch (s) {
+      case "foo":
+        System.out.println(1);
+        break;
+      default:
+        System.out.println(2);
+        break;
+      case "bar":
+        System.out.println(3);
+    }
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/convertSwitchToIf/beforeDefaultMiddleFallIn.java

@@ -0,0 +1,15 @@
+// "Replace 'switch' with 'if'" "false"
+class X {
+  void m(String s) {
+    swi<caret>tch (s) {
+      case "foo":
+        System.out.println(1);
+      default:
+        System.out.println(2);
+        break;
+      case "bar":
+        System.out.println(3);
+        break;
+    }
+  }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/convertSwitchToIf/beforeDefaultMiddleFallOut.java

@@ -0,0 +1,15 @@
+// "Replace 'switch' with 'if'" "false"
+class X {
+  void m(String s) {
+    swi<caret>tch (s) {
+      case "foo":
+        System.out.println(1);
+        break;
+      default:
+        System.out.println(2);
+      case "bar":
+        System.out.println(3);
+        break;
+    }
+  }
+}