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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.

Build status Go Report Card GoDoc BCH compliance Coverage Status

Package import

import (


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


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

Composed with AllOf:

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

Matchers so far..

  • is.EqualTo(x)
  • is.EqualToIgnoringWhitespace(string) - compares two strings without comparing their whitespace characters.
  • is.Nil() - value must be nil
  • is.ValueContaining(expected) -- acts like containsAll
  • is.Not(m *Matcher) -- logical not of matcher's result
  • is.MatchForPattern(regex string) -- a string regex expression
  • has.FunctionNamed(string x) - checks if an interface has a function (method)
  • has.FieldNamed(string x) - checks if a struct has a field named x
  • is.AllOf(... *Matcher) - returns true if all matchers match
  • is.AnyOf(... *Matcher) - return true if any matcher matches
  • is.GreaterThan(expected) - checks if actual > expected
  • is.LessThan(expected)
  • is.Empty() - matches if the actual is "", nil or len(actual)==0
  • is.LessThan(x)
  • is.LessThanOrEqualTo(x)
  • is.GreaterThan(x)
  • is.GreaterThanOrEqualTo(x)
  • has.Length(x) - matcher if given value (int or matcher) matches the len of the given
  • has.Prefix(x) - string starts with x
  • has.Suffix(x) - string ends with x
  • has.Key(x) - map has key x
  • has.AllKeys(T x, T y) (or has.AllKeys([]T{x,y})) - finds key of type T in map
  • has.EveryElement(x1...xn) - checks if actual[i] matches corresponding expectation (x[i])
  • has.StructWithValues(map[string]*gocrest.Matcher) - checks if actual[key] matches corresponding expectation (x[key])

For more comprehensive documentation see godoc.

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