From 1701f4a0d5721b4323a78d71875ca95e97d7eb81 Mon Sep 17 00:00:00 2001
From: Brian Ng <bng412@gmail.com>
Date: Tue, 1 Aug 2017 09:00:01 -0500
Subject: [PATCH] Print declare for TSInterfaceDeclaration (#2574)

---
 src/printer.js                                        |  4 ++++
 .../__snapshots__/jsfmt.spec.js.snap                  | 11 +++++++++++
 tests/typescript_declare/declare_interface.ts         |  3 +++
 3 files changed, 18 insertions(+)
 create mode 100644 tests/typescript_declare/declare_interface.ts

diff --git a/src/printer.js b/src/printer.js
index 840fbe02..cecb4667 100644
--- a/src/printer.js
+++ b/src/printer.js
@@ -856,6 +856,10 @@ function genericPrintNoParens(path, options, print, args) {
       ]);
     }
     case "TSInterfaceDeclaration":
+      if (isNodeStartingWithDeclare(n, options)) {
+        parts.push("declare ");
+      }
+
       parts.push(
         n.abstract ? "abstract " : "",
         printTypeScriptModifiers(path, options, print),
diff --git a/tests/typescript_declare/__snapshots__/jsfmt.spec.js.snap b/tests/typescript_declare/__snapshots__/jsfmt.spec.js.snap
index c9fba276..cf2159e6 100644
--- a/tests/typescript_declare/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/typescript_declare/__snapshots__/jsfmt.spec.js.snap
@@ -18,3 +18,14 @@ declare namespace A {
 }
 
 `;
+
+exports[`declare_interface.ts 1`] = `
+declare interface Dictionary<T> {
+  [index: string]: T
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+declare interface Dictionary<T> {
+  [index: string]: T;
+}
+
+`;
diff --git a/tests/typescript_declare/declare_interface.ts b/tests/typescript_declare/declare_interface.ts
new file mode 100644
index 00000000..77a9962c
--- /dev/null
+++ b/tests/typescript_declare/declare_interface.ts
@@ -0,0 +1,3 @@
+declare interface Dictionary<T> {
+  [index: string]: T
+}