Add method and tests for creating channel canvas

conversation.go

@@ -2,6 +2,7 @@ package slack
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"net/url"
 	"strconv"
@@ -796,3 +797,36 @@ func (api *Client) MarkConversationContext(ctx context.Context, channel, ts stri
 	}
 	return response.Err()
 }
+
+// CreateChannelCanvas creates a new canvas in a channel.
+// For more details, see CreateChannelCanvasContext documentation.
+func (api *Client) CreateChannelCanvas(channel string, documentContent DocumentContent) (string, error) {
+	return api.CreateChannelCanvasContext(context.Background(), channel, documentContent)
+}
+
+// CreateChannelCanvasContext creates a new canvas in a channel with a custom context.
+// Slack API docs: https://api.slack.com/methods/conversations.canvases.create
+func (api *Client) CreateChannelCanvasContext(ctx context.Context, channel string, documentContent DocumentContent) (string, error) {
+	values := url.Values{
+		"token":      {api.token},
+		"channel_id": {channel},
+	}
+	if documentContent.Type != "" {
+		documentContentJSON, err := json.Marshal(documentContent)
+		if err != nil {
+			return "", err
+		}
+		values.Add("document_content", string(documentContentJSON))
+	}
+
+	response := struct {
+		SlackResponse
+		CanvasID string `json:"canvas_id"`
+	}{}
+	err := api.postMethod(ctx, "conversations.canvases.create", values, &response)
+	if err != nil {
+		return "", err
+	}
+
+	return response.CanvasID, response.Err()
+}

conversation_test.go

@@ -722,3 +722,34 @@ func TestMarkConversation(t *testing.T) {
 		return
 	}
 }
+
+func createChannelCanvasHandler(rw http.ResponseWriter, r *http.Request) {
+	rw.Header().Set("Content-Type", "application/json")
+	response, _ := json.Marshal(struct {
+		SlackResponse
+		CanvasID string `json:"canvas_id"`
+	}{
+		SlackResponse: SlackResponse{Ok: true},
+		CanvasID:      "F05RQ01LJU0",
+	})
+	rw.Write(response)
+}
+
+func TestCreateChannelCanvas(t *testing.T) {
+	http.HandleFunc("/conversations.canvases.create", createChannelCanvasHandler)
+	once.Do(startServer)
+	api := New("testing-token", OptionAPIURL("http://"+serverAddr+"/"))
+
+	documentContent := DocumentContent{
+		Type:     "markdown",
+		Markdown: "> channel canvas!",
+	}
+
+	canvasID, err := api.CreateChannelCanvas("C1234567890", documentContent)
+	if err != nil {
+		t.Errorf("Failed to create channel canvas: %v", err)
+		return
+	}
+
+	assert.Equal(t, "F05RQ01LJU0", canvasID)
+}