go-testdeep > Operators > Struct

Struct

func Struct(model any, expectedFields ...StructFields) TestDeep

Struct operator compares the contents of a struct or a pointer on a struct against the non-zero values of model (if any) and the values of expectedFields. See SStruct to compares against zero fields without specifying them in expectedFields.

model must be the same type as compared data. If the expected type is anonymous or private, model can be nil. In this case it is considered lazy and determined each time the operator is involved in a match, see below.

expectedFields can be omitted, if no zero entries are expected and no TestDeep operators are involved. If expectedFields contains more than one item, all items are merged before their use, from left to right.

td.Cmp(t, got, td.Struct(
  Person{
    Name: "John Doe",
  },
  td.StructFields{
    "Children": 4,
  },
  td.StructFields{
    "Age":      td.Between(40, 45),
    "Children": 0, // overwrite 4
  }),
)

It is an error to set a non-zero field in model AND to set the same field in expectedFields, as in such cases the Struct operator does not know if the user wants to override the non-zero model field value or if it is an error. To explicitly override a non-zero model in expectedFields, just prefix its name with a “>” (followed by some optional spaces), as in:

td.Cmp(t, got, td.Struct(
  Person{
    Name:     "John Doe",
    Age:      23,
    Children: 4,
  },
  td.StructFields{
    "> Age":     td.Between(40, 45),
    ">Children": 0, // spaces after ">" are optional
  }),
)

expectedFields can also contain regexps or shell patterns to match multiple fields not explicitly listed in model and in expectedFields. Regexps are prefixed by “=~” or “!~” to respectively match or don’t-match. Shell patterns are prefixed by “=” or “!” to respectively match or don’t-match.

td.Cmp(t, got, td.Struct(
  Person{
    Name: "John Doe",
  },
  td.StructFields{
    "=*At":     td.Lte(time.Now()), // matches CreatedAt & UpdatedAt fields using shell pattern
    "=~^[a-z]": td.Ignore(),        // explicitly ignore private fields using a regexp
  }),
)

When several patterns can match a same field, it is advised to tell go-testdeep in which order patterns should be tested, as once a pattern matches a field, the other patterns are ignored for this field. To do so, each pattern can be prefixed by a number, as in:

td.Cmp(t, got, td.Struct(
  Person{
    Name: "John Doe",
  },
  td.StructFields{
    "1=*At":     td.Lte(time.Now()),
    "2=~^[a-z]": td.NotNil(),
  }),
)

This way, “*At” shell pattern is always used before “^[a-z]” regexp, so if a field “createdAt” exists it is tested against time.Now() and never against NotNil. A pattern without a prefix number is the same as specifying “0” as prefix.

To make it clearer, some spaces can be added, as well as bigger numbers used:

td.Cmp(t, got, td.Struct(
  Person{
    Name: "John Doe",
  },
  td.StructFields{
    " 900 =  *At":    td.Lte(time.Now()),
    "2000 =~ ^[a-z]": td.NotNil(),
  }),
)

The following example combines all possibilities:

td.Cmp(t, got, td.Struct(
  Person{
    NickName: "Joe",
  },
  td.StructFields{
    "Firstname":               td.Any("John", "Johnny"),
    "1 =  *[nN]ame":           td.NotEmpty(), // matches LastName, lastname, …
    "2 !  [A-Z]*":             td.NotZero(),  // matches all private fields
    "3 =~ ^(Crea|Upda)tedAt$": td.Gte(time.Now()),
    "4 !~ ^(Dogs|Children)$":  td.Zero(),   // matches all remaining fields except Dogs and Children
    "5 =~ .":                  td.NotNil(), // matches all remaining fields (same as "5 = *")
  }),
)

If the expected type is private to the current package, it cannot be passed as model. To overcome this limitation, model can be nil, it is then considered as lazy. This way, the model is automatically set during each match to the same type (still requiring struct or struct pointer) of the compared data. Similarly, testing an anonymous struct can be boring as all fields have to be re-declared to define model. A nil model avoids that:

got := struct {
  name string
  age  int
}{"Bob", 42}
td.Cmp(t, got, td.Struct(nil, td.StructFields{"age": td.Between(40, 42)}))

During a match, all expected fields must be found to succeed. Non-expected fields (and so zero model fields) are ignored.

TypeBehind method returns the reflect.Type of model.

See also SStruct.

See also Struct godoc.

Examples

Base example

Overwrite_model example

Patterns example

Lazy_model example

CmpStruct shortcut

func CmpStruct(t TestingT, got, model any, expectedFields StructFields, args ...any) bool

CmpStruct is a shortcut for:

td.Cmp(t, got, td.Struct(model, expectedFields), args...)

See above for details.

Struct optional parameter expectedFields is here mandatory. nil value should be passed to mimic its absence in original Struct call.

Returns true if the test is OK, false if it fails.

If t is a *T then its Config field is inherited.

args… are optional and allow to name the test. This name is used in case of failure to qualify the test. If len(args) > 1 and the first item of args is a string and contains a ‘%’ rune then fmt.Fprintf is used to compose the name, else args are passed to fmt.Fprint. Do not forget it is the name of the test, not the reason of a potential failure.

See also CmpStruct godoc.

Examples

Base example

Overwrite_model example

Patterns example

Lazy_model example

T.Struct shortcut

func (t *T) Struct(got, model any, expectedFields StructFields, args ...any) bool

Struct is a shortcut for:

t.Cmp(got, td.Struct(model, expectedFields), args...)

See above for details.

Struct optional parameter expectedFields is here mandatory. nil value should be passed to mimic its absence in original Struct call.

Returns true if the test is OK, false if it fails.

See also T.Struct godoc.

Examples

Base example

Overwrite_model example

Patterns example

Lazy_model example