Add MustCollector API for pusher

Signed-off-by: kun <oiooj@qq.com>

prometheus/push/push.go

@@ -168,6 +168,16 @@ func (p *Pusher) Collector(c prometheus.Collector) *Pusher {
 	return p
 }
 
+// MustCollector works like Collector but registers any number of
+// Collectors and panics upon the first registration that causes an
+// error.
+//
+// For convenience, this method returns a pointer to the Pusher itself.
+func (p *Pusher) MustCollector(c ...prometheus.Collector) *Pusher {
+	p.registerer.MustRegister(c...)
+	return p
+}
+
 // Grouping adds a label pair to the grouping key of the Pusher, replacing any
 // previously added label pair with the same label name. Note that setting any
 // labels in the grouping key that are already contained in the metrics to push

prometheus/push/push_test.go

@@ -107,6 +107,22 @@ func TestPush(t *testing.T) {
 		t.Error("unexpected path:", lastPath)
 	}
 
+	// use MustCollectors, all good.
+	if err := New(pgwOK.URL, "testjob").
+		MustCollector(metric1, metric2).
+		Push(); err != nil {
+		t.Fatal(err)
+	}
+	if lastMethod != http.MethodPut {
+		t.Errorf("got method %q for Push, want %q", lastMethod, http.MethodPut)
+	}
+	if !bytes.Equal(lastBody, wantBody) {
+		t.Errorf("got body %v, want %v", lastBody, wantBody)
+	}
+	if lastPath != "/metrics/job/testjob" {
+		t.Error("unexpected path:", lastPath)
+	}
+
 	// Add some Collectors, with nil grouping, all good.
 	if err := New(pgwOK.URL, "testjob").
 		Collector(metric1).