Fix crash on class fields that don't end in a semicolon (#271)

Fixes #235

The previous code always ate the next token after a class field, which was a
semicolon in all test cases so far. However, if the class field didn't end in a
semicolon, it would eat the first token of the next class body member, which
would confuse all downstream code and lead to errors.

This means we end up leaving semicolons around in class bodies where class
fields were, but this shouldn't cause problems, and it seems best to keep the
transforms simple.

src/util/getClassInfo.ts

@@ -104,7 +104,6 @@ export default function getClassInfo(
           classInitializers.push(`this${nameCode} =${expressionCode}`);
         }
       }
-      tokens.nextToken();
       fieldRanges.push({start: statementStartIndex, end: tokens.currentIndex()});
     }
   }

test/flow-test.ts

@@ -54,8 +54,8 @@ describe("transform flow", () => {
     `,
       `"use strict";
       class C {
-        
-        
+        ;
+        ;
       }
     `,
     );

test/sucrase-test.ts

@@ -284,7 +284,7 @@ describe("sucrase", () => {
     `,
       `"use strict";
       class A {
-        
+        ;
       } A.x = 3;
     `,
       {transforms: ["jsx", "imports", "typescript"]},
@@ -300,7 +300,7 @@ describe("sucrase", () => {
     `,
       `"use strict"; var _class;
       const A = (_class = class {
-        
+        ;
       }, _class.x = 3, _class)
     `,
       {transforms: ["jsx", "imports", "typescript"]},
@@ -316,7 +316,7 @@ describe("sucrase", () => {
     `,
       `"use strict";${ESMODULE_PREFIX}
        class C {
-        
+        ;
       } C.x = 3; exports.default = C;
     `,
       {transforms: ["jsx", "imports", "typescript"]},
@@ -337,8 +337,8 @@ describe("sucrase", () => {
       var _A = require('A'); var _A2 = _interopRequireDefault(_A);
       var _B = require('B'); var _B2 = _interopRequireDefault(_B);
       class C {constructor() { this.a = _A2.default; }
-        
-        
+        ;
+        ;
       } C.b = _B2.default;
     `,
       {transforms: ["jsx", "imports", "typescript"]},
@@ -505,4 +505,50 @@ describe("sucrase", () => {
       {transforms: ["jsx", "imports", "typescript"]},
     );
   });
+
+  it("handles a static class field without a semicolon", () => {
+    assertResult(
+      `
+      class A {
+        static b = {}
+        c () {
+          const d = 1;
+        }
+      }
+    `,
+      `"use strict";
+      class A {
+        
+        c () {
+          const d = 1;
+        }
+      } A.b = {};
+    `,
+      {transforms: ["imports"]},
+    );
+  });
+
+  it("handles a class with class field bound methods", () => {
+    assertResult(
+      `
+      export class Observer {
+        update = (v: any) => {}
+        complete = () => {}
+        error = (err: any) => {}
+      }
+      
+      export default function() {}
+    `,
+      `"use strict";${ESMODULE_PREFIX}
+       class Observer {constructor() { this.update = (v) => {};this.complete = () => {};this.error = (err) => {}; }
+        
+        
+        
+      } exports.Observer = Observer;
+      
+      exports. default = function() {}
+    `,
+      {transforms: ["imports", "typescript"]},
+    );
+  });
 });

test/types-test.ts

@@ -119,8 +119,8 @@ describe("type transforms", () => {
     `,
       `"use strict";
       class A {constructor() { this.x = 2;this.y = {}; }
-        
-        
+        ;
+        ;
       }
     `,
     );
@@ -135,7 +135,7 @@ describe("type transforms", () => {
     `,
       `"use strict";
       class A {
-        
+        ;
       }
     `,
     );

test/typescript-test.ts

@@ -53,7 +53,7 @@ describe("typescript transform", () => {
     `,
       `"use strict";
       class A {
-        
+        ;
          c() {
           return "hi";
         }
@@ -74,7 +74,7 @@ describe("typescript transform", () => {
     `,
       `"use strict";
       class A {
-        
+        ;
         constructor() {;this.x = 1;
           this.y = 2;
         }
@@ -95,7 +95,7 @@ describe("typescript transform", () => {
     `,
       `"use strict";
       class A extends B {
-        
+        ;
         constructor(a) {
           super(a);this.x = 1;;
         }
@@ -113,7 +113,7 @@ describe("typescript transform", () => {
     `,
       `"use strict";
       class A {constructor() { this.x = 1; }
-        
+        ;
       }
     `,
     );
@@ -128,7 +128,7 @@ describe("typescript transform", () => {
     `,
       `"use strict";
       class A extends B {constructor(...args) { super(...args); this.x = 1; }
-        
+        ;
       }
     `,
     );
@@ -143,7 +143,7 @@ describe("typescript transform", () => {
     `,
       `"use strict";
       class A extends B {constructor(...args2) { super(...args2); this.args = 1; }
-        
+        ;
       }
     `,
     );
@@ -307,8 +307,8 @@ describe("typescript transform", () => {
     `,
       `"use strict";
       class A {constructor() { this.f = function() {}; }
-        
-        
+        ;
+        ;
       }
     `,
     );
@@ -362,9 +362,9 @@ describe("typescript transform", () => {
     `,
       `"use strict";
       class A {constructor() { this[a + b] = 3;this[0] = 1;this["Hello, world"] = 2; }
-        
-        
-        
+        ;
+        ;
+        ;
       }
     `,
     );
@@ -698,7 +698,7 @@ describe("typescript transform", () => {
     `,
       `"use strict";
       class A {
-        
+        ;
          constructor() {;this.x = 1;
         }
       }
@@ -834,7 +834,7 @@ describe("typescript transform", () => {
     `,
       `"use strict";
       class A {
-        
+        ;
         getFoo() {
           return foo;
         }
@@ -968,7 +968,7 @@ describe("typescript transform", () => {
     `,
       `"use strict";
       class A {constructor() { this.n = 3; }
-        
+        ;
       }
     `,
     );