gocrest

A hamcrest-like assertion library for Go. GoCrest matchers are composable, self-describing and can be strung together in a more readable form to create flexible assertions.

Inspired by Hamcrest.

Package import

import (
  "github.com/corbym/gocrest/by"
  "github.com/corbym/gocrest/then"
  "github.com/corbym/gocrest/is"
  "github.com/corbym/gocrest/has"
)

Example:

then.AssertThat(testing, "hi", is.EqualTo("bye").Reason("we are going"))

output:

we are going
Expected: value equal to <bye>
     but: <hi>

Composed with AllOf:

then.AssertThat(t, "abcdef", is.AllOf(is.StringContaining("abc"), is.LessThan("ghi")))

Asynchronous Matching (v1.0.8 onwards):

// Reader
then.WithinFiveSeconds(t, func(eventually gocrest.TestingT) {
	then.AssertThat(eventually, by.Reading(slowReader, 1024), is.EqualTo([]byte("abcdefghijklmnopqrstuv")))
})

// Channels
then.Eventually(t, time.Second*5, time.Second, func(eventually gocrest.TestingT) {
	then.AssertThat(eventually, by.Channelling(channel), is.EqualTo(3).Reason("should not fail"))
})

// Calling a function
then.AssertThat(t, by.Calling(myFunc, inputValue), is.EqualTo(expectedOutput))

// Multiple assertions
then.WithinTenSeconds(t, func(eventually gocrest.TestingT) {
	then.AssertThat(eventually, by.Channelling(channel), is.EqualTo(3).Reason("should not fail"))
	then.AssertThat(eventually, by.Channelling(channelTwo), is.EqualTo("11").Reason("This is unreachable"))
})

v.1.1.0 - generics

Changes all the matchers to use generics instead of reflection. Some still use a bit of reflection, e.g. TypeName etc.

Other major changes:

• ValueContaining has been split into StringContaining, MapContaining, MapContainingValues, MapMatchingValues, ArrayContaining and ArrayMatching.

• No longer panics with unknown types, as types will fail at compile time. Some idiosyncrasies with the generic types do exist, but this is language specific;

• Map matchers generally need to know the type of the map key values explicitly or the compiler will complain, e.g.

then.AssertThat(testing, map[string]bool{"hi": true, "bye": true}, has.AllKeys[string, bool]("hi", "bye"))

• Length matchers are type-specific: use has.Length[T]() for arrays/slices, has.StringLength() for strings, and has.MapLength[K, V]() for maps. Matcher variants (has.LengthMatching, has.StringLengthMatching, has.MapLengthMatching) accept a *Matcher[int] instead of a plain int.
• is.LessThan() and is.GreaterThan() (and by extension is.GreaterThanOrEqualTo and is.LessThanOrEqualTo) no longer work on complex types. This is because the complex types do not support the comparison operators (yet, somehow, they could be compared by reflection 🤷 )

See the matcher_test.go file for full usage.

Matchers so far..

• is.EqualTo(x)
• is.EqualToIgnoringWhitespace(string) - compares two strings without comparing their whitespace characters.
• is.Nil() - error value must be nil
• is.NilArray() - array/slice value must be nil
• is.NilMap() - map value must be nil
• is.NilPtr() - pointer value must be nil
• is.True() - boolean value must be true
• is.False() - boolean value must be false
• is.StringContaining(expected) -- acts like containsAll
• is.MapContaining(expected) -- acts like containsAll
• is.MapContainingValues(expected) -- acts like containsAll
• is.MapMatchingValues(expected) -- acts like containsAll
• is.ArrayContaining(expected) -- acts like containsAll
• is.ArrayMatching(expected) -- acts like containsAll
• is.Not(m *Matcher) -- logical not of matcher's result
• is.MatchForPattern(regex string) -- a string regex expression
• is.AllOf(... *Matcher) - returns true if all matchers match
• is.AnyOf(... *Matcher) - returns true if any matcher matches
• is.GreaterThan(expected) - checks if actual > expected
• is.GreaterThanOrEqualTo(expected)
• is.LessThan(expected) - checks if actual < expected
• is.LessThanOrEqualTo(expected)
• is.Empty() - matches if the actual slice has len == 0
• is.EmptyString() - matches if the actual string is ""
• is.EmptyMap() - matches if the actual map has len == 0
• has.FunctionNamed(x string) - checks if an interface has a function (method) named x
• has.FieldNamed(x string) - checks if a struct has a field named x
• has.Length[T](expected int) - matches if the length of an array/slice equals expected
• has.StringLength(expected int) - matches if the length of a string equals expected
• has.MapLength(expected int) - matches if the length of a map equals expected
• has.LengthMatching[A](expected *Matcher[int]) - matches if the length of an array/slice satisfies expected matcher
• has.StringLengthMatching(expected *Matcher[int]) - matches if the length of a string satisfies expected matcher
• has.MapLengthMatching(expected *Matcher[int]) - matches if the length of a map satisfies expected matcher
• has.Prefix(x) - string starts with x
• has.Suffix(x) - string ends with x
• has.Key(x) - map has key x
• has.AllKeys(x ...K) - matches if all given keys are present in the map
• has.TypeName(expected string) - matches if the actual value's type name equals expected
• has.TypeNameMatches(expected *Matcher[string]) - matches if the actual value's type name satisfies expected matcher
• has.EveryElement(x1...xn) - checks if actual[i] matches corresponding expectation (x[i])
• has.StructWithValues(expects StructMatchers[B]) - checks if actual struct fields match their corresponding matchers

For more comprehensive documentation see godoc.