feat: support doomed transaction scope on test cases (ali-sdk#58)

Author: xujihui1985

lib/client.js

@@ -98,6 +98,41 @@ proto.beginTransactionScope = function* (scope, ctx) {
   }
 };
 
+/**
+ * doomed to be rollbacked after transaction scope
+ * useful on writing test that depend on database
+ *
+ * @param {Function} scope - scope with code
+ * @param {Object} [ctx] - transaction env context, like koa's ctx.
+ *   To make sure only one active transaction on this ctx.
+ * @return {Object} - scope return result
+ */
+proto.beginDoomedTransactionScope = function* (scope, ctx) {
+  ctx = ctx || {};
+  if (!ctx._transactionConnection) {
+    ctx._transactionConnection = yield this.beginTransaction();
+    ctx._transactionScopeCount = 1;
+  } else {
+    ctx._transactionScopeCount++;
+  }
+  const tran = ctx._transactionConnection;
+  try {
+    const result = yield scope(tran);
+    ctx._transactionScopeCount--;
+    if (ctx._transactionScopeCount === 0) {
+      ctx._transactionConnection = null;
+    }
+    return result;
+  } catch (err) {
+    if (ctx._transactionConnection) {
+      ctx._transactionConnection = null;
+    }
+    throw err;
+  } finally {
+    yield tran.rollback();
+  }
+};
+
 proto.end = function(callback) {
   // callback style
   if (callback) {

test/client.test.js

@@ -415,6 +415,34 @@ describe('client.test.js', function() {
     });
   });
 
+  describe('beginDoomedTransactionScope(scope)', function() {
+
+    it('should insert 0 rows in a doomed transaction with ctx', function* () {
+      const ctx = {};
+      const db = this.db;
+
+      function* insert() {
+        return yield db.beginDoomedTransactionScope(function* (conn) {
+          yield conn.query('insert into ??(name, email, gmt_create, gmt_modified) \
+            values(?, ?, now(), now())',
+            [ table, prefix + 'beginDoomedTransactionScopeCtx1', prefix + 'm@beginDoomedTransactionScopeCtx1.com' ]);
+          yield conn.query('insert into ??(name, email, gmt_create, gmt_modified) \
+            values(?, ?, now(), now())',
+            [ table, prefix + 'beginDoomedTransactionScopeCtx2', prefix + 'm@beginDoomedTransactionScopeCtx1.com' ]);
+          return true;
+        }, ctx);
+      }
+
+      yield insert();
+
+      const rows = yield db.query('select * from ?? where email=? order by id',
+        [ table, prefix + 'm@beginDoomedTransactionScopeCtx1.com' ]);
+      assert.equal(rows.length, 0);
+      assert.equal(ctx._transactionConnection, null);
+      assert.equal(ctx._transactionScopeCount, 0);
+    });
+  });
+
   describe('get(table, obj, options), select(table, options)', function() {
     before(function* () {
       let result = yield this.db.insert(table, {