partial evaluation (#244)

Makefile

@@ -58,6 +58,11 @@ test:
 test/ci: build
 	./bin/terramate list --changed
 
+## start fuzzying to generate some new corpus/find errors
+.PHONY: test/fuzz
+test/fuzz:
+	go test ./hcl/eval -fuzz=FuzzPartialEval
+
 ## Build terramate into bin directory
 .PHONY: build
 build:

generate/generate_hcl_test.go

@@ -106,7 +106,7 @@ func TestHCLGeneration(t *testing.T) {
 									expr("local_a", "global.local_a"),
 									expr("local_b", "global.local_b"),
 									expr("local_c", "global.local_c"),
-									expr("local_d", "try(global.local_d.field, null)"),
+									expr("local_d", "tm_try(global.local_d.field, null)"),
 								),
 							),
 						),

generate/generate_report_test.go

@@ -251,6 +251,8 @@ func assertReportHasError(t *testing.T, report generate.Report, err error) {
 func assertEqualReports(t *testing.T, got, want generate.Report) {
 	t.Helper()
 	if diff := cmp.Diff(got, want); diff != "" {
+		t.Errorf("got %s", got)
+		t.Errorf("want %s", want)
 		t.Errorf("got(-) want(+)")
 		t.Fatal(diff)
 	}

generate/genhcl/genhcl.go

@@ -119,17 +119,17 @@ func Load(rootdir string, sm stack.Metadata, globals terramate.Globals) (StackHC
 
 		gen := hclwrite.NewEmptyFile()
 		if err := hcl.CopyBody(gen.Body(), loadedHCL.block.Body, evalctx); err != nil {
-			return StackHCLs{}, fmt.Errorf(
-				"%w: stack %q block %q: %v",
+			evalErr := fmt.Errorf(
+				"%w: stack %q block %q",
 				ErrEval,
 				stackpath,
 				name,
-				err,
 			)
+			return StackHCLs{}, errutil.Chain(evalErr, err)
 		}
 		res.hcls[name] = HCL{
 			origin: loadedHCL.origin,
-			body:   gen.Bytes(),
+			body:   hclwrite.Format(gen.Bytes()),
 		}
 	}
 

generate/genhcl/genhcl_hclwrite_test.go

@@ -0,0 +1,63 @@
+// Copyright 2022 Mineiros GmbH
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package genhcl_test
+
+import "github.com/mineiros-io/terramate/test/hclwrite"
+
+// useful function aliases to build HCL documents
+
+func hcldoc(builders ...hclwrite.BlockBuilder) *hclwrite.Block {
+	return hclwrite.BuildHCL(builders...)
+}
+
+func generateHCL(builders ...hclwrite.BlockBuilder) *hclwrite.Block {
+	return hclwrite.BuildBlock("generate_hcl", builders...)
+}
+
+func block(name string, builders ...hclwrite.BlockBuilder) *hclwrite.Block {
+	return hclwrite.BuildBlock(name, builders...)
+}
+
+func terraform(builders ...hclwrite.BlockBuilder) *hclwrite.Block {
+	return hclwrite.BuildBlock("terraform", builders...)
+}
+
+func globals(builders ...hclwrite.BlockBuilder) *hclwrite.Block {
+	return hclwrite.BuildBlock("globals", builders...)
+}
+
+func content(builders ...hclwrite.BlockBuilder) *hclwrite.Block {
+	return hclwrite.BuildBlock("content", builders...)
+}
+
+func labels(labels ...string) hclwrite.BlockBuilder {
+	return hclwrite.Labels(labels...)
+}
+
+func expr(name string, expr string) hclwrite.BlockBuilder {
+	return hclwrite.Expression(name, expr)
+}
+
+func str(name string, val string) hclwrite.BlockBuilder {
+	return hclwrite.String(name, val)
+}
+
+func number(name string, val int64) hclwrite.BlockBuilder {
+	return hclwrite.NumberInt(name, val)
+}
+
+func boolean(name string, val bool) hclwrite.BlockBuilder {
+	return hclwrite.Boolean(name, val)
+}