Basic tests

The connection, browse, and read/write recipes most client libraries run first. All target opcua-no-security (port 4840) unless noted.

Connection tests

Basic connect

1. Open opc.tcp://localhost:4840/UA/TestServer
2. Create anonymous session
3. Browse root → expect to find "Objects"
4. Browse Objects → expect to find "TestServer"
5. Close session

Pass: every step succeeds without error.

GetEndpoints

GetEndpoints("opc.tcp://localhost:4840/UA/TestServer")
→ returns exactly 1 EndpointDescription:
    securityPolicy:  http://opcfoundation.org/UA/SecurityPolicy#None
    securityMode:    None
    userIdentityTokens: [Anonymous]

For opcua-all-security (4843), expect 11 endpoints. For opcua-certificate (4842), 6.

Connection refused on unsupported policy

Connect to opcua-userpass (4841) requesting None / None → expect failure (the server doesn't offer it).

Read tests

Single scalar read

read(ns=1;s=TestServer/DataTypes/Scalar/BooleanValue)
→ DataValue { value=true, statusCode=Good }

Repeat for every scalar type — see Scalar types for the full list of initial values.

Batch read

read([
  ns=1;s=TestServer/DataTypes/Scalar/BooleanValue,
  ns=1;s=TestServer/DataTypes/Scalar/Int32Value,
  ns=1;s=TestServer/DataTypes/Scalar/StringValue,
])
→ 3 DataValues, each Good

For opcua-no-security, the server caps MaxNodesPerRead at 5. Asking for 6 nodes returns BadTooManyOperations. Use this to test the limit error path.

Read non-Value attribute

read(ns=1;s=TestServer/DataTypes/Scalar/BooleanValue, attribute=DisplayName)
→ "BooleanValue" (LocalizedText)

read(..., attribute=AccessLevel)
→ 3 (CurrentRead | CurrentWrite)

Write tests

Single scalar write

write(ns=1;s=TestServer/DataTypes/Scalar/BooleanValue, value=false)
→ Good
read(ns=1;s=TestServer/DataTypes/Scalar/BooleanValue)
→ value=false

Round-trip every type

for each scalar type T:
    sample = make_test_value(T)
    write(ns=1;s=TestServer/DataTypes/Scalar/{T}Value, value=sample)
    assert read(...).value == sample

Strong assertion that your client wires up every encoder.

Read-only rejection

write(ns=1;s=TestServer/DataTypes/ReadOnly/Int32_RO, value=42)
→ Bad_NotWritable

Type mismatch

write(ns=1;s=TestServer/DataTypes/Scalar/Int32Value, value="not a number")
→ Bad_TypeMismatch (or your library coerces silently — check)

Browse tests

Browse Objects → find TestServer

browse(ns=0;i=85)  # Objects folder
→ result contains a reference to ns=1;s=TestServer

Browse TestServer → 9 folders

browse(ns=1;s=TestServer)
→ 9 references (or 10 on opcua-sks)
   [DataTypes, Methods, Dynamic, Events, Alarms,
    Historical, Structures, ExtensionObjects, AccessControl]

Recursive browse

recursive_browse(ns=1;s=TestServer, maxDepth=20)
→ approximately 300 nodes

Exact count varies by server config (toggled features) but is stable across restarts.

Browse with filter

browse(ns=1;s=TestServer, nodeClassFilter=Variable)
→ only variable children (none directly — they're in subfolders)

browse(ns=1;s=TestServer/DataTypes/Scalar, nodeClassFilter=Variable)
→ 21 variables

Endpoint discovery on each server

For each of the 10 classic servers, call GetEndpoints and verify the count matches:

Multi-server checklist

For a comprehensive smoke test:

A test matrix that runs these three operations against each server flushes out 80% of integration bugs.

What "Good" means

OPC UA Good = 0x00000000. A successful read has:

statusCode = Good
sourceTimestamp = a recent DateTime
serverTimestamp = a recent DateTime (often equal to sourceTimestamp)
value           = the actual value

Any other status code in 0x80xxxxxx is a bad read and should fail the test. 0x40xxxxxx is uncertain — the value may be present but flagged as unreliable; treat per your library's policy.

Where to read next

• Subscription and method tests — the next layer.
• Security tests — cert and auth recipes.