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fix: Make TestAgent and TestWorkspaceAgentPTY less flaky #1562

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Merged
merged 3 commits into from
May 18, 2022
Merged

fix: Make TestAgent and TestWorkspaceAgentPTY less flaky #1562

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5aa982e
fix: Make TestAgent/ReconnectingPTY more robust
dwahler May 18, 2022
bf9c363
Sleep before sending command
dwahler May 18, 2022
0696b40
Fix TestWorkspaceAgentPTY
dwahler May 18, 2022
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27 changes: 20 additions & 7 deletions agent/agent_test.go
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
package agent_test

import (
"bufio"
"context"
"encoding/json"
"fmt"
Expand Down Expand Up @@ -204,6 +205,11 @@ func TestAgent(t *testing.T) {
id := uuid.NewString()
netConn, err := conn.ReconnectingPTY(id, 100, 100)
require.NoError(t, err)
bufRead := bufio.NewReader(netConn)

// Brief pause to reduce the likelihood that we send keystrokes while
// the shell is simultaneously sending a prompt.
time.Sleep(100 * time.Millisecond)
Comment on lines +210 to +212
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This should properly be buffered on the server-side, were you seeing it differently?

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I don't think it's a problem with the server, just an inherent race. The actual issue I was seeing was that the test was sending the command before it received the prompt, which means the command text actually got echoed twice. This is because after bash prints the prompt, it helpfully re-echoes anything that was pending in the input buffer, in order to make line editing work properly.

For instance, if you type sleep 10<ENTER>echo foo<ENTER> quickly, you get output on your terminal that looks like:

$ sleep 10
echo foo
$ echo foo
foo

It would certainly be cleaner to wait for the prompt and then send the input, but I'm not sure that we can easily/portably do that.

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Ahh I see. Makes sense!


data, err := json.Marshal(agent.ReconnectingPTYRequest{
Data: "echo test\r\n",
Expand All @@ -212,28 +218,35 @@ func TestAgent(t *testing.T) {
_, err = netConn.Write(data)
require.NoError(t, err)

findEcho := func() {
expectLine := func(matcher func(string) bool) {
for {
read, err := netConn.Read(data)
line, err := bufRead.ReadString('\n')
require.NoError(t, err)
if strings.Contains(string(data[:read]), "test") {
if matcher(line) {
break
}
}
}
matchEchoCommand := func(line string) bool {
return strings.Contains(line, "echo test")
}
matchEchoOutput := func(line string) bool {
return strings.Contains(line, "test") && !strings.Contains(line, "echo")
}

// Once for typing the command...
findEcho()
expectLine(matchEchoCommand)
// And another time for the actual output.
findEcho()
expectLine(matchEchoOutput)

_ = netConn.Close()
netConn, err = conn.ReconnectingPTY(id, 100, 100)
require.NoError(t, err)
bufRead = bufio.NewReader(netConn)

// Same output again!
findEcho()
findEcho()
expectLine(matchEchoCommand)
expectLine(matchEchoOutput)
})

t.Run("Dial", func(t *testing.T) {
Expand Down
25 changes: 19 additions & 6 deletions coderd/workspaceagents_test.go
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Original file line number Diff line number Diff line change
@@ -1,11 +1,13 @@
package coderd_test

import (
"bufio"
"context"
"encoding/json"
"runtime"
"strings"
"testing"
"time"

"github.com/google/uuid"
"github.com/pion/webrtc/v3"
Expand Down Expand Up @@ -230,6 +232,11 @@ func TestWorkspaceAgentPTY(t *testing.T) {
require.NoError(t, err)
_, err = conn.Write(data)
require.NoError(t, err)
bufRead := bufio.NewReader(conn)

// Brief pause to reduce the likelihood that we send keystrokes while
// the shell is simultaneously sending a prompt.
time.Sleep(100 * time.Millisecond)

data, err = json.Marshal(agent.ReconnectingPTYRequest{
Data: "echo test\r\n",
Expand All @@ -238,16 +245,22 @@ func TestWorkspaceAgentPTY(t *testing.T) {
_, err = conn.Write(data)
require.NoError(t, err)

findEcho := func() {
expectLine := func(matcher func(string) bool) {
for {
read, err := conn.Read(data)
line, err := bufRead.ReadString('\n')
require.NoError(t, err)
if strings.Contains(string(data[:read]), "test") {
return
if matcher(line) {
break
}
}
}
matchEchoCommand := func(line string) bool {
return strings.Contains(line, "echo test")
}
matchEchoOutput := func(line string) bool {
return strings.Contains(line, "test") && !strings.Contains(line, "echo")
}

findEcho()
findEcho()
expectLine(matchEchoCommand)
expectLine(matchEchoOutput)
}