| package main |
| |
| // Tests of interface conversions and type assertions. |
| |
| type I0 interface { |
| } |
| type I1 interface { |
| f() |
| } |
| type I2 interface { |
| f() |
| g() |
| } |
| |
| type C0 struct{} |
| type C1 struct{} |
| |
| func (C1) f() {} |
| |
| type C2 struct{} |
| |
| func (C2) f() {} |
| func (C2) g() {} |
| |
| func main() { |
| var i0 I0 |
| var i1 I1 |
| var i2 I2 |
| |
| // Nil always causes a type assertion to fail, even to the |
| // same type. |
| if _, ok := i0.(I0); ok { |
| panic("nil i0.(I0) succeeded") |
| } |
| if _, ok := i1.(I1); ok { |
| panic("nil i1.(I1) succeeded") |
| } |
| if _, ok := i2.(I2); ok { |
| panic("nil i2.(I2) succeeded") |
| } |
| |
| // Conversions can't fail, even with nil. |
| _ = I0(i0) |
| |
| _ = I0(i1) |
| _ = I1(i1) |
| |
| _ = I0(i2) |
| _ = I1(i2) |
| _ = I2(i2) |
| |
| // Non-nil type assertions pass or fail based on the concrete type. |
| i1 = C1{} |
| if _, ok := i1.(I0); !ok { |
| panic("C1 i1.(I0) failed") |
| } |
| if _, ok := i1.(I1); !ok { |
| panic("C1 i1.(I1) failed") |
| } |
| if _, ok := i1.(I2); ok { |
| panic("C1 i1.(I2) succeeded") |
| } |
| |
| i1 = C2{} |
| if _, ok := i1.(I0); !ok { |
| panic("C2 i1.(I0) failed") |
| } |
| if _, ok := i1.(I1); !ok { |
| panic("C2 i1.(I1) failed") |
| } |
| if _, ok := i1.(I2); !ok { |
| panic("C2 i1.(I2) failed") |
| } |
| |
| // Conversions can't fail. |
| i1 = C1{} |
| if I0(i1) == nil { |
| panic("C1 I0(i1) was nil") |
| } |
| if I1(i1) == nil { |
| panic("C1 I1(i1) was nil") |
| } |
| } |
