Channel Type Support

go-testgen detects and correctly handles all Go channel types — chan, chan<-, <-chan — in both function parameters and return values.

Detection

The analyzer inspects AST *ast.ChanType nodes and the types.Chan type from go/packages, setting:

• IsChannel — whether the parameter/result is a channel
• ChanDir — direction: 0 (bidirectional), 1 (send-only), 2 (receive-only)

Generated Output

Channel types are handled in three places:

typeToString

Preserves channel direction in string representation:

chan int       → "chan int"
chan<- string  → "chan<- string"
<-chan []byte  → "<-chan []byte"

qualifiedTypeName

Correctly qualifies channel types with package prefixes:

chan *user.User     → "chan *userDomain.User"
<-chan []string     → "<-chan cache.Pkg.StringList"

placeholderValue

Returns nil for all channel types — the only valid zero value.

Example

// Source function
func ChannelRecvReturn(ctx context.Context) <-chan *SomeType {
    ch := make(chan *SomeType)
    go func() {
        defer close(ch)
        ch <- &SomeType{ID: "1", Name: "one"}
    }()
    return ch
}

go-testgen gen ./internal/pkg ChannelRecvReturn

The generated test captures the <-chan *SomeType return correctly with a nil placeholder for the channel parameter.