fix(typescript): look at source to determine export = statement (#1868)

src/printer.js

@@ -3386,7 +3386,20 @@ function printExportDeclaration(path, options, print) {
   const parts = ["export "];
 
   if (decl["default"] || decl.type === "ExportDefaultDeclaration") {
-    parts.push("default ");
+    // Temp fix, delete after https://github.com/eslint/typescript-eslint-parser/issues/304
+    if (
+      decl.declaration &&
+      /=/.test(
+        options.originalText.slice(
+          util.locStart(decl),
+          util.locStart(decl.declaration)
+        )
+      )
+    ) {
+      parts.push("= ");
+    } else {
+      parts.push("default ");
+    }
   }
 
   parts.push(

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

@@ -8,3 +8,22 @@ export function match(): string /* the matching pattern */
 a;
 
 `;
+
+exports[`export.ts 1`] = `
+declare module "hello" {
+    export default Hello;
+}
+
+declare module "hello" {
+    export = Hello;
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+declare module "hello" {
+  export default Hello;
+}
+
+declare module "hello" {
+  export = Hello;
+}
+
+`;

tests/typescript_export/export.ts

@@ -0,0 +1,7 @@
+declare module "hello" {
+    export default Hello;
+}
+
+declare module "hello" {
+    export = Hello;
+}