fix: safe integer bounds conversion (#576)

* fix: safe integer bound and added test cases

* test: added more unit tests for outside of bounds

Author: laljikanjareeya

src/mutation.ts

@@ -111,7 +111,7 @@ export class Mutation {
       // tslint:disable-next-line no-any
       const num = Long.fromBytes(buf as any).toNumber();
 
-      if (Number.MIN_SAFE_INTEGER < num && num < Number.MAX_SAFE_INTEGER) {
+      if (Number.isSafeInteger(num)) {
         return num;
       }
     }

test/mutation.ts

@@ -56,6 +56,55 @@ describe('Bigtable/Mutation', function() {
 
         assert.strictEqual(num, decoded);
       });
+
+      it('should convert a base64 encoded MIN_SAFE_INTEGER number when true', function() {
+        const num = Number.MIN_SAFE_INTEGER;
+        const encoded = Buffer.from(Long.fromNumber(num).toBytesBE()).toString(
+          'base64'
+        );
+        const decoded = Mutation.convertFromBytes(encoded, {
+          isPossibleNumber: true,
+        });
+
+        assert.strictEqual(num, decoded);
+      });
+
+      it('should convert a base64 encoded MAX_SAFE_INTEGER number when true', function() {
+        const num = Number.MAX_SAFE_INTEGER;
+        const encoded = Buffer.from(Long.fromNumber(num).toBytesBE()).toString(
+          'base64'
+        );
+        const decoded = Mutation.convertFromBytes(encoded, {
+          isPossibleNumber: true,
+        });
+
+        assert.strictEqual(num, decoded);
+      });
+
+      it('should not convert a base64 encoded smaller than MIN_SAFE_INTEGER number when true', function() {
+        const num = Number.MIN_SAFE_INTEGER - 100;
+        const encoded = Buffer.from(Long.fromNumber(num).toBytesBE()).toString(
+          'base64'
+        );
+        const decoded = Mutation.convertFromBytes(encoded, {
+          isPossibleNumber: true,
+        });
+
+        assert.notStrictEqual(num, decoded);
+      });
+
+      it('should not convert a base64 encoded larger than MAX_SAFE_INTEGER number when true', function() {
+        const num = Number.MAX_SAFE_INTEGER + 100;
+        const encoded = Buffer.from(Long.fromNumber(num).toBytesBE()).toString(
+          'base64'
+        );
+        const decoded = Mutation.convertFromBytes(encoded, {
+          isPossibleNumber: true,
+        });
+
+        assert.notStrictEqual(num, decoded);
+      });
+
       it('should not convert a base64 encoded number when false', function() {
         const num = 10;
         const encoded = Buffer.from(Long.fromNumber(num).toBytesBE()).toString(