Consider Adding State Check Equivalents to Plan Checks

[bendbennett]

terraform-plugin-testing version

v.1.6.0

Use cases

The plancheck package within terraform-plugin-testing has plan checks which use tfjson.Plan. This provides structured data which is easily traversed and interrogated for the purposes of, for instance, verifying that a specific resource attribute, or output value has a known type and value.

There is an equivalent tfjson.State which is available, and would provide an similarly straightforward way to traverse and interrogate the state for the purposes of verifying, for instance, that a specific resource attribute, or output value has a known type and value.

Attempted solutions

Currently, values in state can be checked by configuring the TestStep.Check field and using either predefined TestCheckFunc functions (e.g., TestCheckNoResourceAttr) or by writing custom TestCheckFunc functions. Checks that use TestCheckFunc functions are constrained by the flatmap syntax that is required to access state values, and by the fact that all values are represented as strings.

Proposal

The proposal is to:

• Add, where relevant, state checks that are equivalent to the previously implemented plan checks.
• Add predefined/built-in state checks that provide equivalent functionality to that provided by the predefined TestCheckFunc functions (e.g., TestCheckNoResourceAttr).

Further Considerations

The deprecation of the predefined TestCheckFunc functions (e.g., TestCheckNoResourceAttr) has been separated from the implementation of state checks, and will now be considered in a subsequent set of changes:

• Consider Multiple Value Checking Interface
• Deprecation of Built-In TestCheckFunc Implementations for Checking Pairs of Values

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