zpages: fix Snapshot int->*int64 changes + tests on count

The signature for countFormatter's arguments was changed
in PR #948 from int to int64 but unfortunately we forgot
to update the int fields from int to the new type.

Issue #948's recommendation was to use uint64 since that
affords us more time to overflow e.g. even at 25QPs
it'd take a couple of millenia to overflow with uint64.

This change completes the change of types of the int variables
but also adds tests that make use of the template functions
and a snapshot and then compare the output or fail. Previously the
tests complained but since they were HTTP tests not attached
to an output buffer that could be inspected, the bug innocently
crept away in standard output and the tests incorrectly passed as in:
* https://ci.appveyor.com/project/opencensusgoteam/opencensus-go/builds/19498802#L700
* https://travis-ci.org/census-instrumentation/opencensus-go/builds/441324783#L1183

This problem was reported by an OpenCensus-Service user in
* census-instrumentation/opencensus-service#123

Fixes #895
Fixes #951

zpages/formatter_test.go

@@ -19,10 +19,9 @@ import "testing"
 
 func TestCountFormatter(t *testing.T) {
 	tests := []struct {
-		in   int64
+		in   uint64
 		want string
 	}{
-		{-1, " "},
 		{0, " "},
 		{1, "1"},
 		{1024, "1024"},

zpages/rpcz.go

@@ -170,9 +170,9 @@ type statSnapshot struct {
 	// TODO: compute hour/minute values from cumulative
 	Method           string
 	Received         bool
-	CountMinute      int
-	CountHour        int
-	CountTotal       int
+	CountMinute      uint64
+	CountHour        uint64
+	CountTotal       uint64
 	AvgLatencyMinute time.Duration
 	AvgLatencyHour   time.Duration
 	AvgLatencyTotal  time.Duration
@@ -185,9 +185,9 @@ type statSnapshot struct {
 	OutputRateMinute float64
 	OutputRateHour   float64
 	OutputRateTotal  float64
-	ErrorsMinute     int
-	ErrorsHour       int
-	ErrorsTotal      int
+	ErrorsMinute     uint64
+	ErrorsHour       uint64
+	ErrorsTotal      uint64
 }
 
 type methodKey struct {
@@ -267,7 +267,7 @@ func (s snapExporter) ExportView(vd *view.Data) {
 			}
 			for _, tag := range row.Tags {
 				if tag.Key == ocgrpc.KeyClientStatus && tag.Value != "OK" {
-					s.ErrorsTotal += int(count)
+					s.ErrorsTotal += uint64(count)
 				}
 			}
 
@@ -281,7 +281,7 @@ func (s snapExporter) ExportView(vd *view.Data) {
 			s.InputRateTotal = computeRate(0, sum)
 
 		case ocgrpc.ClientSentMessagesPerRPCView:
-			s.CountTotal = int(count)
+			s.CountTotal = uint64(count)
 			s.RPCRateTotal = computeRate(0, count)
 
 		case ocgrpc.ClientReceivedMessagesPerRPCView:
@@ -294,7 +294,7 @@ func (s snapExporter) ExportView(vd *view.Data) {
 			}
 			for _, tag := range row.Tags {
 				if tag.Key == ocgrpc.KeyServerStatus && tag.Value != "OK" {
-					s.ErrorsTotal += int(count)
+					s.ErrorsTotal += uint64(count)
 				}
 			}
 
@@ -305,7 +305,7 @@ func (s snapExporter) ExportView(vd *view.Data) {
 			s.OutputRateTotal = computeRate(0, sum)
 
 		case ocgrpc.ServerReceivedMessagesPerRPCView:
-			s.CountTotal = int(count)
+			s.CountTotal = uint64(count)
 			s.RPCRateTotal = computeRate(0, count)
 
 		case ocgrpc.ServerSentMessagesPerRPCView:

zpages/rpcz_test.go

@@ -49,7 +49,7 @@ func TestRpcz(t *testing.T) {
 		t.Fatal("Expected method stats not recorded")
 	}
 
-	if got, want := snapshot.CountTotal, 1; got != want {
+	if got, want := snapshot.CountTotal, uint64(1); got != want {
 		t.Errorf("snapshot.CountTotal = %d; want %d", got, want)
 	}
 }

zpages/templates.go

@@ -57,7 +57,7 @@ func parseTemplate(name string) *template.Template {
 	return template.Must(template.New(name).Funcs(templateFunctions).Parse(string(text)))
 }
 
-func countFormatter(num int64) string {
+func countFormatter(num uint64) string {
 	if num <= 0 {
 		return " "
 	}

zpages/templates_test.go

@@ -0,0 +1,99 @@
+// Copyright 2018, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package zpages
+
+import (
+	"bytes"
+	"html/template"
+	"testing"
+)
+
+const tmplBody = `
+        <td><b>{{.Method}}</b></td>
+        <td></td>
+        <td align="right">{{.CountMinute|count}}</td>
+        <td align="right">{{.CountHour|count}}</td>
+        <td align="right">{{.CountTotal|count}}</td><td></td>
+        <td align="right">{{.AvgLatencyMinute|ms}}</td>
+        <td align="right">{{.AvgLatencyHour|ms}}</td>
+        <td align="right">{{.AvgLatencyTotal|ms}}</td><td></td>
+        <td align="right">{{.RPCRateMinute|rate}}</td>
+        <td align="right">{{.RPCRateHour|rate}}</td>
+        <td align="right">{{.RPCRateTotal|rate}}</td><td></td>
+        <td align="right">{{.InputRateMinute|datarate}}</td>
+        <td align="right">{{.InputRateHour|datarate}}</td>
+        <td align="right">{{.InputRateTotal|datarate}}</td><td></td>
+        <td align="right">{{.OutputRateMinute|datarate}}</td>
+        <td align="right">{{.OutputRateHour|datarate}}</td>
+        <td align="right">{{.OutputRateTotal|datarate}}</td><td></td>
+        <td align="right">{{.ErrorsMinute|count}}</td>
+        <td align="right">{{.ErrorsHour|count}}</td>
+        <td align="right">{{.ErrorsTotal|count}}</td><td></td>
+`
+
+var tmpl = template.Must(template.New("countTest").Funcs(templateFunctions).Parse(tmplBody))
+
+func TestTemplateFuncs(t *testing.T) {
+	buf := new(bytes.Buffer)
+	sshot := &statSnapshot{
+		Method:           "Foo",
+		CountMinute:      1e9,
+		CountHour:        5000,
+		CountTotal:       1e12,
+		AvgLatencyMinute: 10000,
+		AvgLatencyHour:   1000,
+		AvgLatencyTotal:  20000,
+		RPCRateMinute:    2000,
+		RPCRateHour:      5000,
+		RPCRateTotal:     75000,
+		InputRateMinute:  75000,
+		InputRateHour:    75000,
+		InputRateTotal:   75000,
+		OutputRateMinute: 75000,
+		OutputRateHour:   75000,
+		OutputRateTotal:  75000,
+		ErrorsMinute:     120000000,
+		ErrorsHour:       75000000,
+		ErrorsTotal:      7500000,
+	}
+	if err := tmpl.Execute(buf, sshot); err != nil {
+		t.Fatalf("Failed to execute template: %v", err)
+	}
+	want := `
+        <td><b>Foo</b></td>
+        <td></td>
+        <td align="right">1.000 G </td>
+        <td align="right">5000</td>
+        <td align="right">1.000 T </td><td></td>
+        <td align="right">0.010</td>
+        <td align="right">0.001</td>
+        <td align="right">0.020</td><td></td>
+        <td align="right">2000.000</td>
+        <td align="right">5000.000</td>
+        <td align="right">75000.000</td><td></td>
+        <td align="right">0.075</td>
+        <td align="right">0.075</td>
+        <td align="right">0.075</td><td></td>
+        <td align="right">0.075</td>
+        <td align="right">0.075</td>
+        <td align="right">0.075</td><td></td>
+        <td align="right">120.000 M </td>
+        <td align="right">75.000 M </td>
+        <td align="right">7.500 M </td><td></td>
+`
+	if g, w := buf.String(), want; g != w {
+		t.Errorf("Output mismatch:\nGot:\n\t%s\nWant:\n\t%s", g, w)
+	}
+}