62 lines
2.2 KiB
Markdown
62 lines
2.2 KiB
Markdown
|
# Dot
|
||
|
|
|
||
|
|
The dot module generates a DOT file representation of a dependency graph.
|
||
|
|
|
||
|
|
## Interpreting the graph
|
||
|
|
|
||
|
|
The graph should be read from left to right. The leftmost node in the graph (the root node) depends
|
||
|
|
on its dependency tree to the right. An arrow from node_a to node_b in the graph means that node_b
|
||
|
|
is consumed by node_a and that node_b is a parameter of node_a. The rendered graph holds the
|
||
|
|
following kinds of nodes,
|
||
|
|
|
||
|
|
**Nodes:**
|
||
|
|
|
||
|
|
- *Constructors* [Rectangles]: Takes parameters and produces results.
|
||
|
|
- *Results* [Ovals]: Results inside a constructor are produced by that constructor. Results are consumed
|
||
|
|
directly by other constructors and/or part of a group of results.
|
||
|
|
- *Groups* [Diamonds]: Represent value groups in [fx](https://godoc.org/go.uber.org/fx). Multiple results can form a group. Any
|
||
|
|
result linked to a group by an edge are members of that group. A group is a collection of results.
|
||
|
|
Groups can also be parameters of constructors.
|
||
|
|
|
||
|
|
**Edges:**
|
||
|
|
|
||
|
|
- *Solid Arrows*: An arrow from node_a to node_b means that node_b is a parameter of node_a and that
|
||
|
|
node_a depends on node_b.
|
||
|
|
- *Dashed Arrows*: A dashed arrow from node_a to node_b represents an optional dependency that node_a
|
||
|
|
has on node_b.
|
||
|
|
|
||
|
|
**Graph Colors:**
|
||
|
|
|
||
|
|
- *Red*: Graph nodes are the root cause failures.
|
||
|
|
- *Orange*: Graph nodes are the transitive failures.
|
||
|
|
|
||
|
|
## Testing and verifying changes
|
||
|
|
|
||
|
|
Unit tests and visualize golden tests are run with
|
||
|
|
|
||
|
|
```shell
|
||
|
|
$ make test
|
||
|
|
```
|
||
|
|
|
||
|
|
You can visualize the effect of your code changes by visualizing generated test graphs as pngs.
|
||
|
|
|
||
|
|
In the dig root directory, generate the graph DOT files with respect to your latest code changes.
|
||
|
|
|
||
|
|
```shell
|
||
|
|
$ go test -generate
|
||
|
|
```
|
||
|
|
|
||
|
|
Assuming that you have [graphviz](https://www.graphviz.org/) installed and are in the testdata directory,
|
||
|
|
generate a png image representation of a graph for viewing.
|
||
|
|
|
||
|
|
```shell
|
||
|
|
$ dot -Tpng ${name_of_dot_file_in_testdata}.dot -o ${name_of_dot_file_in_testdata}.png
|
||
|
|
$ open ${name_of_dot_file_in_testdata}.png
|
||
|
|
```
|
||
|
|
|
||
|
|
## Graph Pruning
|
||
|
|
|
||
|
|
If dot.Visualize is used to visualize an error graph, non-failing nodes are pruned out of the graph
|
||
|
|
to make the error graph more readable to the user. Pruning increases readability since successful
|
||
|
|
nodes clutter the graph and do not help the user debug errors.
|