Test Syntax

In wvlet, you can insert test statements in the middle of a query. For example, you can test the number of rows, column names, or the query result itself:

person.json

[
  {"id":1, "name": "alice", "age": 10 },
  {"id":2, "name": "bob", "age": 24 },
  {"id":3, "name": "clark", "age": 40 }
]

from 'person.json'
-- Test the query size and schema
test _.size should be 3
test _.columns should be ['id', 'name', 'age']
test _.columns should contain 'name'
test _.columns should not contain 'address'

-- Test the query output. Surrounding white spaces will be trimmed:
test _.output should be """
┌──────┬────────┬──────┐
│  id  │  name  │ age  │
│ long │ string │ long │
├──────┼────────┼──────┤
│    1 │ alice  │   10 │
│    2 │ bob    │   24 │
│    3 │ clark  │   40 │
├──────┴────────┴──────┤
│ 3 rows               │
└──────────────────────┘
"""

-- Test the query result in JSON format
test _.json should be """
{"id":1,"name":"alice","age":10}
{"id":2,"name":"bob","age":24}
{"id":3,"name":"clark","age":40}
"""
test _.json should contain """{"id":2,"name":"bob","age":24}"""
test _.json should not contain """{"id":4,"name":"david","age":32}"""

-- Test rows with arrays
test _.rows should contain [1, "alice", 10]
test _.rows should contain [2, "bob", 24]
test _.rows should not contain [5, "eric", 18]
test _.rows should be [
  [1, "alice", 10],
  [2, "bob", 24],
  [3, "clark", 40],
]

These tests will be ignored in the default query execution. Only in the test-run mode, these test expressions will be evaluated.

Result Inspection Functions

Syntax	Output
_.size	The number of rows in the query result
_.columns	The column names in the query result
_.output	Pretty print query result
_.json	JSON line format of result rows
_.rows	rows in array of array representation

Test Expressions

Syntax	Description
x should be y	Test if the value of x is equal to y
x should not be y	Test if the value of x is not equal to y
x should contain y	Test if the string value of x contains y
x should not contain y	Test if the string value of x does not contain y