No need to wrap String.formatted for local variable or field (#121)

Author: Tim te Beek

src/main/java/org/openrewrite/java/migrate/lang/StringFormatted.java

@@ -63,10 +63,9 @@ public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext p) {
             }
 
             List<Expression> arguments = mi.getArguments();
-            String template = String.format(
-                    arguments.get(0) instanceof J.Literal || arguments.get(0) instanceof J.MethodInvocation
-                            ? "#{any(java.lang.String)}.formatted(%s)"
-                            : "(#{any(java.lang.String)}).formatted(%s)",
+            String template = String.format(wrapperNotNeeded(arguments.get(0))
+                    ? "#{any(java.lang.String)}.formatted(%s)"
+                    : "(#{any(java.lang.String)}).formatted(%s)",
                     String.join(", ", Collections.nCopies(arguments.size() - 1, "#{any()}")));
             maybeRemoveImport("java.lang.String.format");
             return mi.withTemplate(
@@ -76,6 +75,12 @@ public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext p) {
                     mi.getCoordinates().replace(),
                     arguments.toArray());
         }
+
+        private static boolean wrapperNotNeeded(Expression expression) {
+            return expression instanceof J.Identifier
+                    || expression instanceof J.Literal
+                    || expression instanceof J.MethodInvocation;
+        }
     }
 
     @Override

src/test/kotlin/org/openrewrite/java/migrate/lang/StringFormattedTest.kt

@@ -139,6 +139,44 @@ class StringFormattedTest : RewriteTest {
         """)
     )
 
+    @Test
+    @Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/77")
+    fun doNotWrapLocalVariable() = rewriteRun(
+        java("""
+            class A {
+                String someMethod() {
+                    String fmt = "foo %s";
+                    String str = String.format(fmt, "a");
+                }
+            }
+        """,
+        """
+            class A {
+                String someMethod() {
+                    String fmt = "foo %s";
+                    String str = fmt.formatted("a");
+                }
+            }
+        """)
+    )
+
+    @Test
+    @Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/77")
+    fun doNotWrapField() = rewriteRun(
+        java("""
+            class A {
+                static final String fmt = "foo %s";
+                String str = String.format(fmt, "a");
+            }
+        """,
+        """
+            class A {
+                static final String fmt = "foo %s";
+                String str = fmt.formatted("a");
+            }
+        """)
+    )
+
     @Test
     @Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/77")
     fun removeStaticImport() = rewriteRun(