terraform: add TransitiveReductionTransformer

This commit is contained in:
Mitchell Hashimoto 2015-02-27 19:18:04 -08:00
parent ed2075e384
commit 903e49162d
3 changed files with 69 additions and 0 deletions

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resource "aws_instance" "A" {}
resource "aws_instance" "B" {
A = "${aws_instance.A.id}"
}
resource "aws_instance" "C" {
A = "${aws_instance.A.id}"
B = "${aws_instance.B.id}"
}

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package terraform
// TransitiveReductionTransformer is a GraphTransformer that performs
// finds the transitive reduction of the graph. For a definition of
// transitive reduction, see Wikipedia.
type TransitiveReductionTransformer struct{}
func (t *TransitiveReductionTransformer) Transform(g *Graph) error {
// If the graph isn't valid, skip the transitive reduction.
// We don't error here because Terraform itself handles graph
// validation in a better way, or we assume it does.
if err := g.Validate(); err != nil {
return nil
}
// Do it
g.TransitiveReduction()
return nil
}

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package terraform
import (
"strings"
"testing"
)
func TestTransitiveReductionTransformer(t *testing.T) {
mod := testModule(t, "transform-trans-reduce-basic")
g := Graph{Path: RootModulePath}
{
tf := &ConfigTransformer{Module: mod}
if err := tf.Transform(&g); err != nil {
t.Fatalf("err: %s", err)
}
}
{
transform := &TransitiveReductionTransformer{}
if err := transform.Transform(&g); err != nil {
t.Fatalf("err: %s", err)
}
}
actual := strings.TrimSpace(g.String())
expected := strings.TrimSpace(testTransformTransReduceBasicStr)
if actual != expected {
t.Fatalf("bad:\n\n%s", actual)
}
}
const testTransformTransReduceBasicStr = `
aws_instance.A
aws_instance.B
aws_instance.A
aws_instance.C
aws_instance.B
`