gs-predicate/docs/predicates-key-value.md

Predicates: Key-Value

Refer to Terminology for information about specific terms.

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Description

These predicates are focused on reasoning about keys and their associated (or not associated) values.

Input

All key-value predicates accept a single input: some key-value provider. This is the state referenced by the predicates.

This provider can answer two questions:

• Does the given key exist?
• What is the value associated with a given key?

Predicate: Key Exists

Matches if the key-value provider contains the given key.

Predicate: Value Equals

Given some key K and expected value EV, this predicate matches if:

• There is some value V associated with K.
• V is equal to EV.

Predicate: Value Not Equals

Given some key K and unexpected value UV, this predicate matches if:

• There is some value V associated with K.
• V is not equal to UV.

Predicate: String Contains

Important

This predicate is only supported for string values.

Given some key K and string S, this predicate matches if:

• There is some value V associated with K.
• V contains the substring S.

Examples

S	V	Result
""	""	match
""	"a"	match
"a"	""	miss
"a"	"abc"	match
"ab"	"abc"	match
"b"	"abc"	match
"bc"	"abc"	match
"c"	"abc"	match
"d"	"abc"	miss
"abc"	"abc"	match

Predicate: String Starts With

Important

This predicate is only supported for string values.

Given some key K and prefix P, this predicate matches if:

• There is some value V associated with K.
• V starts with the prefix P.

Examples

P	V	Result
""	""	match
""	"a"	match
"a"	""	miss
"a"	"abc"	match
"ab"	"abc"	match
"b"	"abc"	miss
"d"	"abc"	miss
"abc"	"abc"	match

Predicate: String Ends With

Important

This predicate is only supported for string values.

Given some key K and suffix S, this predicate matches if:

• There is some value V associated with K.
• V ends with the suffix S.

Examples

S	V	Result
""	""	match
""	"a"	match
"a"	""	miss
"a"	"abc"	miss
"bc"	"abc"	match
"c"	"abc"	match
"d"	"abc"	miss
"abc"	"abc"	match