Fix error dropping when making requests

msgraph/client.go

@@ -58,6 +58,10 @@ type Uri struct {
 // RetryableErrorHandler ensures that the response is returned after exhausting retries for a request
 // We can't return an error here, or net/http will not return the response
 func RetryableErrorHandler(resp *http.Response, err error, numTries int) (*http.Response, error) {
+	if resp == nil {
+		return nil, err
+	}
+
 	return resp, nil
 }
 

msgraph/client_test.go

@@ -0,0 +1,72 @@
+package msgraph
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"strings"
+	"testing"
+)
+
+func TestClient_GetWithError(t *testing.T) {
+	// This creates a listener on a random available port.
+	l, err := net.Listen("tcp", ":0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	port := l.Addr().(*net.TCPAddr).Port
+	l.Close()
+
+	hc := NewClient(VersionBeta)
+	hc.Endpoint = fmt.Sprintf("https://localhost:%d/", port)
+	hc.RetryableClient.RetryMax = 2
+
+	_, _, _, err = hc.Get(context.Background(), GetHttpRequestInput{
+		ConsistencyFailureFunc: RetryOn404ConsistencyFailureFunc,
+		ValidStatusCodes:       []int{http.StatusOK},
+		Uri: Uri{
+			Entity: "/users/test",
+		},
+	})
+	if err == nil {
+		t.Error("expected to get an error, got nil")
+	}
+	if msg := err.Error(); !strings.Contains(msg, "connect: connection refused") {
+		log.Fatalf("got %s, want message with 'connection refused'", msg)
+	}
+}
+
+func TestClient_GetWithResponseAndError(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/beta/users/test" {
+			n, _ := strconv.Atoi(r.FormValue("n"))
+			if n < 15 {
+				http.Redirect(w, r, fmt.Sprintf("%s?n=%d", r.URL.Path, 1), http.StatusTemporaryRedirect)
+				return
+			}
+		}
+	}))
+	defer ts.Close()
+
+	hc := NewClient(VersionBeta)
+	hc.Endpoint = ts.URL
+	hc.RetryableClient.RetryMax = 2
+
+	_, _, _, err := hc.Get(context.Background(), GetHttpRequestInput{
+		ConsistencyFailureFunc: RetryOn404ConsistencyFailureFunc,
+		ValidStatusCodes:       []int{http.StatusOK},
+		Uri: Uri{
+			Entity: "/users/test",
+		},
+	})
+	if err == nil {
+		t.Error("expected to get an error, got nil")
+	}
+	if msg := err.Error(); !strings.Contains(msg, "stopped after 10 redirects") {
+		log.Fatalf("got %s, want message with 'stopped after 10 redirects'", msg)
+	}
+}