Fix flow extends not breaking out into new lines (#5244)

src/language-js/printer-estree.js

@@ -2651,7 +2651,11 @@ function printPathNoParens(path, options, print, args) {
         parts.push(
           group(
             indent(
-              concat([line, "extends ", join(", ", path.map(print, "extends"))])
+              concat([
+                line,
+                "extends ",
+                indent(join(concat([",", line]), path.map(print, "extends")))
+              ])
             )
           )
         );

tests/interface/__snapshots__/jsfmt.spec.js.snap

@@ -19,6 +19,52 @@ export class Environment2 extends GenericEnvironment<
 > {
   m() {};
 };
+
+// Declare Interface Break
+declare interface ExtendsOne extends ASingleInterface {
+  x: string;
+}
+
+declare interface ExtendsLarge extends ASingleInterfaceWithAReallyReallyReallyReallyLongName {
+  x: string;
+}
+
+declare interface ExtendsMany extends Interface1, Interface2, Interface3, Interface4, Interface5, Interface6, Interface7 {
+  x: string;
+}
+
+// Interface declaration break
+interface ExtendsOne extends ASingleInterface {
+  x: string;
+}
+
+interface ExtendsLarge extends ASingleInterfaceWithAReallyReallyReallyReallyLongName {
+  x: string;
+}
+
+interface ExtendsMany extends Interface1, Interface2, Interface3, Interface4, Interface5, Interface6, Interface7 {
+  s: string;
+}
+
+// Generic Types
+interface ExtendsOne extends ASingleInterface<string> {
+  x: string;
+}
+
+interface ExtendsLarge extends ASingleInterfaceWithAReallyReallyReallyReallyLongName<string> {
+  x: string;
+}
+
+interface ExtendsMany
+  extends ASingleGenericInterface<Interface1, Interface2, Interface3, Interface4, Interface5, Interface6, Interface7> {
+  x: string;
+}
+
+interface ExtendsManyWithGenerics
+  extends InterfaceOne, InterfaceTwo, ASingleGenericInterface<Interface1, Interface2, Interface3, Interface4, Interface5, Interface6, Interface7>, InterfaceThree {
+
+    x: string;
+  }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 export interface Environment1
   extends GenericEnvironment<SomeType, AnotherType, YetAnotherType> {
@@ -36,6 +82,87 @@ export class Environment2 extends GenericEnvironment<
   m() {}
 }
 
+// Declare Interface Break
+declare interface ExtendsOne extends ASingleInterface {
+  x: string;
+}
+
+declare interface ExtendsLarge
+  extends ASingleInterfaceWithAReallyReallyReallyReallyLongName {
+  x: string;
+}
+
+declare interface ExtendsMany
+  extends Interface1,
+    Interface2,
+    Interface3,
+    Interface4,
+    Interface5,
+    Interface6,
+    Interface7 {
+  x: string;
+}
+
+// Interface declaration break
+interface ExtendsOne extends ASingleInterface {
+  x: string;
+}
+
+interface ExtendsLarge
+  extends ASingleInterfaceWithAReallyReallyReallyReallyLongName {
+  x: string;
+}
+
+interface ExtendsMany
+  extends Interface1,
+    Interface2,
+    Interface3,
+    Interface4,
+    Interface5,
+    Interface6,
+    Interface7 {
+  s: string;
+}
+
+// Generic Types
+interface ExtendsOne extends ASingleInterface<string> {
+  x: string;
+}
+
+interface ExtendsLarge
+  extends ASingleInterfaceWithAReallyReallyReallyReallyLongName<string> {
+  x: string;
+}
+
+interface ExtendsMany
+  extends ASingleGenericInterface<
+      Interface1,
+      Interface2,
+      Interface3,
+      Interface4,
+      Interface5,
+      Interface6,
+      Interface7
+    > {
+  x: string;
+}
+
+interface ExtendsManyWithGenerics
+  extends InterfaceOne,
+    InterfaceTwo,
+    ASingleGenericInterface<
+      Interface1,
+      Interface2,
+      Interface3,
+      Interface4,
+      Interface5,
+      Interface6,
+      Interface7
+    >,
+    InterfaceThree {
+  x: string;
+}
+
 `;
 
 exports[`module.js - flow-verify 1`] = `

tests/interface/break.js

@@ -16,3 +16,49 @@ export class Environment2 extends GenericEnvironment<
 > {
   m() {};
 };
+
+// Declare Interface Break
+declare interface ExtendsOne extends ASingleInterface {
+  x: string;
+}
+
+declare interface ExtendsLarge extends ASingleInterfaceWithAReallyReallyReallyReallyLongName {
+  x: string;
+}
+
+declare interface ExtendsMany extends Interface1, Interface2, Interface3, Interface4, Interface5, Interface6, Interface7 {
+  x: string;
+}
+
+// Interface declaration break
+interface ExtendsOne extends ASingleInterface {
+  x: string;
+}
+
+interface ExtendsLarge extends ASingleInterfaceWithAReallyReallyReallyReallyLongName {
+  x: string;
+}
+
+interface ExtendsMany extends Interface1, Interface2, Interface3, Interface4, Interface5, Interface6, Interface7 {
+  s: string;
+}
+
+// Generic Types
+interface ExtendsOne extends ASingleInterface<string> {
+  x: string;
+}
+
+interface ExtendsLarge extends ASingleInterfaceWithAReallyReallyReallyReallyLongName<string> {
+  x: string;
+}
+
+interface ExtendsMany
+  extends ASingleGenericInterface<Interface1, Interface2, Interface3, Interface4, Interface5, Interface6, Interface7> {
+  x: string;
+}
+
+interface ExtendsManyWithGenerics
+  extends InterfaceOne, InterfaceTwo, ASingleGenericInterface<Interface1, Interface2, Interface3, Interface4, Interface5, Interface6, Interface7>, InterfaceThree {
+
+    x: string;
+  }