terraform: add TransitiveReductionTransformer
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resource "aws_instance" "A" {}
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resource "aws_instance" "B" {
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A = "${aws_instance.A.id}"
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}
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resource "aws_instance" "C" {
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A = "${aws_instance.A.id}"
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B = "${aws_instance.B.id}"
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}
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package terraform
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// TransitiveReductionTransformer is a GraphTransformer that performs
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// finds the transitive reduction of the graph. For a definition of
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// transitive reduction, see Wikipedia.
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type TransitiveReductionTransformer struct{}
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func (t *TransitiveReductionTransformer) Transform(g *Graph) error {
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// If the graph isn't valid, skip the transitive reduction.
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// We don't error here because Terraform itself handles graph
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// validation in a better way, or we assume it does.
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if err := g.Validate(); err != nil {
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return nil
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}
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// Do it
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g.TransitiveReduction()
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return nil
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}
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package terraform
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import (
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"strings"
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"testing"
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)
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func TestTransitiveReductionTransformer(t *testing.T) {
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mod := testModule(t, "transform-trans-reduce-basic")
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g := Graph{Path: RootModulePath}
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{
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tf := &ConfigTransformer{Module: mod}
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if err := tf.Transform(&g); err != nil {
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t.Fatalf("err: %s", err)
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}
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}
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{
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transform := &TransitiveReductionTransformer{}
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if err := transform.Transform(&g); err != nil {
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t.Fatalf("err: %s", err)
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}
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}
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actual := strings.TrimSpace(g.String())
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expected := strings.TrimSpace(testTransformTransReduceBasicStr)
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if actual != expected {
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t.Fatalf("bad:\n\n%s", actual)
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}
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}
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const testTransformTransReduceBasicStr = `
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aws_instance.A
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aws_instance.B
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aws_instance.A
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aws_instance.C
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aws_instance.B
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`
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