fix: return the same value when resolving request multiple times

Before this commit, when calling fetchr on the client using the
promise API and resolving it multiple times would lead to undefined
values.

We now make sure to always return the fetch promise in
httpRequest. But doing so, broke the abort behavior since we would not
return an FetchrHttpRequest to the user from fetchr methods. To fix
that, we now save an instance of FetchrHttpRequest in the Request
class and added an abort method to the later one to call
FetchrHttpRequest.abort method.

libs/fetcher.client.js

@@ -38,6 +38,7 @@ function Request(operation, resource, options) {
     this._body = null;
     this._clientConfig = {};
     this._startTime = 0;
+    this._request = null;
 }
 
 /**
@@ -104,22 +105,39 @@ Request.prototype._captureMetaAndStats = function (err, result) {
     }
 };
 
+Request.prototype._send = function () {
+    if (this._request) {
+        return this._request;
+    }
+
+    this._startTime = Date.now();
+    this._request = httpRequest(normalizeOptions(this));
+    var captureMetaAndStats = this._captureMetaAndStats.bind(this);
+
+    this._request.then(
+        function (result) {
+            captureMetaAndStats(null, result);
+            return result;
+        },
+        function (err) {
+            captureMetaAndStats(err);
+            throw err;
+        },
+    );
+
+    return this._request;
+};
+
 Request.prototype.then = function (resolve, reject) {
-    return this.end(function (err, data, meta) {
-        if (err) {
-            reject(err);
-        } else {
-            resolve({ data, meta });
-        }
-    });
+    return this._send().then(resolve, reject);
 };
 
 Request.prototype.catch = function (reject) {
-    return this.end(function (err) {
-        if (err) {
-            reject(err);
-        }
-    });
+    return this._send().catch(reject);
+};
+
+Request.prototype.abort = function () {
+    return this._request.abort();
 };
 
 /**
@@ -136,30 +154,20 @@ Request.prototype.end = function (callback) {
         );
     }
 
-    var self = this;
-    self._startTime = Date.now();
+    this._send();
 
-    var onResponse = function (err, result) {
-        self._captureMetaAndStats(err, result);
-        if (callback) {
-            setTimeout(function () {
-                callback(err, result && result.data, result && result.meta);
-            });
-        } else if (err) {
-            throw err;
-        } else {
-            return result;
-        }
-    };
+    if (callback) {
+        this._request.then(
+            function (result) {
+                callback(null, result && result.data, result && result.meta);
+            },
+            function (err) {
+                callback(err);
+            },
+        );
+    }
 
-    return httpRequest(normalizeOptions(self)).then(
-        function (result) {
-            return onResponse(null, result);
-        },
-        function (err) {
-            return onResponse(err);
-        },
-    );
+    return this._request;
 };
 
 /**

libs/util/httpRequest.js

@@ -151,13 +151,11 @@ FetchrHttpRequest.prototype.abort = function () {
 };
 
 FetchrHttpRequest.prototype.then = function (resolve, reject) {
-    this._request = this._request.then(resolve, reject);
-    return this;
+    return this._request.then(resolve, reject);
 };
 
 FetchrHttpRequest.prototype.catch = function (reject) {
-    this._request = this._request.catch(reject);
-    return this;
+    return this._request.catch(reject);
 };
 
 function httpRequest(options) {