provider: rearrange files to ease reading/addition

The known providers are now put into a separated files, which helps with
adding new supported one to the default list.

estimation.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/spf13/afero"
 
-	"github.com/cycloidio/terracost/aws"
 	"github.com/cycloidio/terracost/cost"
 	"github.com/cycloidio/terracost/terraform"
 )
@@ -16,9 +15,7 @@ import (
 // It uses the Backend to retrieve the pricing data.
 func EstimateTerraformPlan(ctx context.Context, backend Backend, plan io.Reader, providerInitializers ...terraform.ProviderInitializer) (*cost.Plan, error) {
 	if len(providerInitializers) == 0 {
-		providerInitializers = []terraform.ProviderInitializer{
-			aws.TerraformProviderInitializer,
-		}
+		providerInitializers = getDefaultProviders()
 	}
 
 	tfplan := terraform.NewPlan(providerInitializers...)
@@ -27,7 +24,7 @@ func EstimateTerraformPlan(ctx context.Context, backend Backend, plan io.Reader,
 	}
 
 	priorQueries, err := tfplan.ExtractPriorQueries()
-	if err != nil && err != terraform.ErrNoQueries {
+	if err != nil {
 		return nil, err
 	}
 	prior, err := cost.NewState(ctx, backend, priorQueries)
@@ -52,9 +49,7 @@ func EstimateTerraformPlan(ctx context.Context, backend Backend, plan io.Reader,
 // It uses the Backend to retrieve the pricing data.
 func EstimateHCL(ctx context.Context, backend Backend, fs afero.Fs, path string, providerInitializers ...terraform.ProviderInitializer) (*cost.Plan, error) {
 	if len(providerInitializers) == 0 {
-		providerInitializers = []terraform.ProviderInitializer{
-			aws.TerraformProviderInitializer,
-		}
+		providerInitializers = getDefaultProviders()
 	}
 
 	plannedQueries, err := terraform.ExtractQueriesFromHCL(fs, providerInitializers, path)

go.sum

@@ -508,6 +508,7 @@ golang.org/x/lint v0.0.0-20190909230951-414d861bb4ac/go.mod h1:6SW0HCj/g11FgYtHl
 golang.org/x/lint v0.0.0-20190930215403-16217165b5de/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
 golang.org/x/lint v0.0.0-20191125180803-fdd1cda4f05f/go.mod h1:5qLYkcX4OjUUV8bRuDixDT3tpyyb+LUpUlRWLxfhWrs=
 golang.org/x/lint v0.0.0-20200130185559-910be7a94367/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
+golang.org/x/lint v0.0.0-20200302205851-738671d3881b h1:Wh+f8QHJXR411sJR8/vRBTZ7YapZaRvUcLFFJhusH0k=
 golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
 golang.org/x/mobile v0.0.0-20190312151609-d3739f865fa6/go.mod h1:z+o9i4GpDbdi3rU15maQ/Ox0txvL9dWGYEHz965HBQE=
 golang.org/x/mobile v0.0.0-20190719004257-d2bd2a29d028/go.mod h1:E/iHnbuqvinMTCcRqshq8CkpyQDoeVncDDYHnLhea+o=
@@ -679,6 +680,7 @@ golang.org/x/tools v0.0.0-20200729194436-6467de6f59a7/go.mod h1:njjCfa9FT2d7l9Bc
 golang.org/x/tools v0.0.0-20200804011535-6c149bb5ef0d/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/tools v0.0.0-20200825202427-b303f430e36d/go.mod h1:njjCfa9FT2d7l9Bc6FUM5FLjQPp3cFF28FI3qnDFljA=
 golang.org/x/tools v0.0.0-20200904185747-39188db58858/go.mod h1:Cj7w3i3Rnn0Xh82ur9kSqwfTHTeVxaDqrfMjpcNT6bE=
+golang.org/x/tools v0.0.0-20201028111035-eafbe7b904eb h1:KVWk3RW1AZlxWum4tYqegLgwJHb5oouozcGM8HfNQaw=
 golang.org/x/tools v0.0.0-20201028111035-eafbe7b904eb/go.mod h1:emZCQorbCU4vsT4fOWvOPXz4eW1wZW4PmDk9uLelYpA=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

provider.go

@@ -0,0 +1,16 @@
+package terracost
+
+import (
+	"github.com/cycloidio/terracost/aws"
+	"github.com/cycloidio/terracost/terraform"
+)
+
+// defaultProviders are the currently known and supported terraform providers
+var defaultProviders = []terraform.ProviderInitializer{
+	aws.TerraformProviderInitializer,
+}
+
+// getDefaultProviders will return the default supported providers of terracost
+func getDefaultProviders() []terraform.ProviderInitializer {
+	return defaultProviders
+}