Loading Fixtures

Loading Test Fixtures

Use @.Load.From(fileName) to load JSON, YAML, or CSV files as test data. Paths are resolved relative to the directory of the current ISL file.

Syntax

$data = @.Load.From("fileName")

• fileName – Path relative to the current file (e.g. fixtures/data.json, ../shared/config.yaml)

Supported Formats

Extension	Description
.json	Parsed as JSON
.yaml, .yml	Parsed as YAML, converted to JSON
.csv	Parsed as CSV; first row = headers, converted to array of objects

All formats are returned as JSON (objects or arrays) for use in assertions.

Examples

JSON

fixtures/user.json:

{"name": "Alice", "age": 30, "active": true}

tests/user.isl:

@test
fun test_loadJson() {
    $user = @.Load.From("fixtures/user.json")
    @.Assert.equal("Alice", $user.name)
    @.Assert.equal(30, $user.age)
    @.Assert.equal(true, $user.active)
}

YAML

fixtures/config.yaml:

key: value
nested:
  count: 10
  items: [a, b, c]

tests/config.isl:

@test
fun test_loadYaml() {
    $config = @.Load.From("fixtures/config.yaml")
    @.Assert.equal("value", $config.key)
    @.Assert.equal(10, $config.nested.count)
    @.Assert.equal(3, $config.nested.items | length)
}

CSV

fixtures/data.csv:

id,name,score
1,Alice,100
2,Bob,85

tests/data.isl:

@test
fun test_loadCsv() {
    $rows = @.Load.From("fixtures/data.csv")
    @.Assert.equal(2, $rows | length)
    @.Assert.equal("Alice", $rows[0].name)
    @.Assert.equal(100, $rows[0].score)
    @.Assert.equal("Bob", $rows[1].name)
}

CSV is parsed with the first row as headers. Each subsequent row becomes an object with those headers as keys.

Path Resolution

Paths are relative to the directory of the current ISL file:

Current file	fileName	Resolved path
tests/sample.isl	fixtures/data.json	tests/fixtures/data.json
tests/sample.isl	../shared/config.yaml	shared/config.yaml
tests/unit/sample.isl	../../fixtures/data.json	fixtures/data.json

Availability

@.Load.From is available only in the test context:

• ✅ When running tests via isl test
• ✅ When running via TransformTestPackage with basePath passed to TransformTestPackageBuilder
• ❌ In regular transform execution (e.g. isl transform)

If basePath is not set (e.g. programmatic use without it), Load.From throws a clear error.

Error Handling

• File not found: Throws with the resolved path
• Unsupported format: Throws for extensions other than .json, .yaml, .yml, .csv
• Parse error: Invalid JSON/YAML/CSV throws during parsing