Added memory ballast e2e behavior test

Added a new test that verifies that the ballast behaves only counts to
virtual memory and is not actually allocated.

Also added `tests/results/BASELINE.md` to act as the baseline test
results file. The TESTRESULTS.md file was modified on every run and it
would change in every PR from every contributor. It added additional
work when one didn't want to include it in a PR which was most of the
time. Only time it should be updated is when someone adds or updates a
new perf test.

testbed/testbed/options.go

@@ -0,0 +1,18 @@
+package testbed
+
+// TestCaseOption defines a TestCase option
+type TestCaseOption struct {
+	option func(t *TestCase)
+}
+
+// Apply takes a TestCase and runs the option function on it
+func (o TestCaseOption) Apply(t *TestCase) {
+	o.option(t)
+}
+
+// WithSkipResults option disables writing out results file for a TestCase
+func WithSkipResults() TestCaseOption {
+	return TestCaseOption{func(t *TestCase) {
+		t.skipResults = true
+	}}
+}

testbed/testbed/test_case.go

@@ -32,6 +32,9 @@ type TestCase struct {
 	// Directory where test case results and logs will be written.
 	resultDir string
 
+	// does not write out results when set to true
+	skipResults bool
+
 	// Agent config file path.
 	agentConfigFile string
 
@@ -60,14 +63,18 @@ type TestCase struct {
 const mibibyte = 1024 * 1024
 
 // NewTestCase creates a new TestCase. It expected agent-config.yaml in the specified directory.
-func NewTestCase(t *testing.T) *TestCase {
+func NewTestCase(t *testing.T, opts ...TestCaseOption) *TestCase {
 	tc := TestCase{}
 
 	tc.t = t
 	tc.ErrorSignal = make(chan struct{})
 	tc.doneSignal = make(chan struct{})
 	tc.startTime = time.Now()
 
+	for _, opt := range opts {
+		opt.Apply(&tc)
+	}
+
 	var err error
 	tc.resultDir, err = filepath.Abs(path.Join("results", t.Name()))
 	if err != nil {
@@ -123,14 +130,16 @@ func (tc *TestCase) SetExpectedMaxRAM(ramMiB uint32) {
 
 // StartAgent starts the agent and redirects its standard output and standard error
 // to "agent.log" file located in the test directory.
-func (tc *TestCase) StartAgent() {
+func (tc *TestCase) StartAgent(args ...string) {
+	args = append(args, "--config")
+	args = append(args, tc.agentConfigFile)
 	logFileName := tc.composeTestResultFileName("agent.log")
 
 	err := tc.agentProc.start(startParams{
 		name:         "Agent",
 		logFilePath:  logFileName,
 		cmd:          testBedConfig.Agent,
-		cmdArgs:      []string{"--config", tc.agentConfigFile},
+		cmdArgs:      args, 
 		resourceSpec: &tc.resourceSpec,
 	})
 
@@ -180,6 +189,16 @@ func (tc *TestCase) StopBackend() {
 	tc.MockBackend.Stop()
 }
 
+// AgentMemoryInfo returns raw memory info struct about the agent 
+// as returned by github.com/shirou/gopsutil/process
+func (tc *TestCase) AgentMemoryInfo() (uint32, uint32, error) {
+	stat, err := tc.agentProc.processMon.MemoryInfo()
+	if err != nil {
+		return 0, 0, err
+	}
+	return uint32(stat.RSS / mibibyte), uint32(stat.VMS / mibibyte), nil
+}
+
 // Stop stops the load generator, the agent and the backend.
 func (tc *TestCase) Stop() {
 	// Stop all components
@@ -190,6 +209,10 @@ func (tc *TestCase) Stop() {
 	// Stop logging
 	close(tc.doneSignal)
 
+	if tc.skipResults {
+		return
+	}
+
 	// Report test results
 
 	rc := tc.agentProc.GetTotalConsumption()

testbed/tests/.gitignore

@@ -1 +1,2 @@
 results/*
+!results/BASELINE.md

testbed/tests/e2e_test.go

@@ -0,0 +1,55 @@
+// Copyright 2019, OpenTelemetry 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 tests contains test cases. To run the tests go to tests directory and run:
+// TESTBED_CONFIG=local.yaml go test -v
+
+package tests
+
+import (
+	"fmt"
+	"testing"
+	"strconv"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/open-telemetry/opentelemetry-service/testbed/testbed"
+)
+
+func TestBallastMemory(t *testing.T) {
+	tests := []struct{
+		ballastSize uint32
+		maxRSS uint32
+	}{
+		{100, 50},
+		{500, 70},
+		{1000, 100},
+	}
+
+	for _, test := range tests {
+		tc := testbed.NewTestCase(t, testbed.WithSkipResults())
+		tc.SetExpectedMaxRAM(test.maxRSS)
+
+		tc.StartAgent("--mem-ballast-size-mib", strconv.Itoa(int(test.ballastSize)))
+
+		rss, vms, err := tc.AgentMemoryInfo()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		assert.True(t, rss <= test.maxRSS, fmt.Sprintf("RSS must be less than or equal to %d", test.maxRSS))
+		assert.True(t, vms > test.ballastSize, fmt.Sprintf("VMS must be greater than %d", test.ballastSize))
+		tc.Stop()
+	}
+}