e2etests-cli: Add stdin test

Closes https://github.com/terrastruct/d2-vscode/issues/56

d2cli/main.go

@@ -153,12 +153,16 @@ func Run(ctx context.Context, ms *xmain.State) (err error) {
 			outputPath = renameExt(inputPath, ".svg")
 		}
 	}
+	if inputPath != "-" {
 		inputPath = filepath.Join(ms.PWD, inputPath)
 		d, err := os.Stat(inputPath)
 		if err == nil && d.IsDir() {
 			inputPath = filepath.Join(inputPath, "index.d2")
 		}
+	}
+	if outputPath != "-" {
 		outputPath = filepath.Join(ms.PWD, outputPath)
+	}
 
 	match := d2themescatalog.Find(*themeFlag)
 	if match == (d2themes.Theme{}) {
@@ -320,6 +324,9 @@ func render(ctx context.Context, ms *xmain.State, compileDur time.Duration, plug
 
 	boardOutputPath := outputPath
 	if len(diagram.Layers) > 0 || len(diagram.Scenarios) > 0 || len(diagram.Steps) > 0 {
+		if outputPath == "-" {
+			return nil, fmt.Errorf("multiboard output cannot be written to stdout")
+		}
 		// Boards with subboards must be self-contained folders.
 		ext := filepath.Ext(boardOutputPath)
 		boardOutputPath = strings.TrimSuffix(boardOutputPath, ext)

e2etests-cli/main_test.go

@@ -1,6 +1,7 @@
 package e2etests_cli
 
 import (
+	"bytes"
 	"context"
 	"os"
 	"path/filepath"
@@ -144,6 +145,22 @@ layers: {
 				testdataIgnoreDiff(t, ".pdf", pdf)
 			},
 		},
+		{
+			name: "stdin",
+			run: func(t *testing.T, ctx context.Context, dir string, env *xos.Env) {
+				stdin := bytes.NewBufferString(`x -> y`)
+				stdout := &bytes.Buffer{}
+				tms := testMain(dir, env, "-")
+				tms.Stdin = stdin
+				tms.Stdout = stdout
+				tms.Start(t, ctx)
+				defer tms.Cleanup(t)
+				err := tms.Wait(ctx)
+				assert.Success(t, err)
+
+				assert.Testdata(t, ".svg", stdout.Bytes())
+			},
+		},
 	}
 
 	ctx := context.Background()

go.mod

@@ -23,7 +23,7 @@ require (
 	golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2
 	gonum.org/v1/plot v0.12.0
 	nhooyr.io/websocket v1.8.7
-	oss.terrastruct.com/util-go v0.0.0-20230303172031-56bcfcdf965d
+	oss.terrastruct.com/util-go v0.0.0-20230303204624-090ad7923dcb
 )
 
 require (

go.sum

@@ -277,6 +277,6 @@ honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWh
 honnef.co/go/tools v0.0.0-20190523083050-ea95bdfd59fc/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
 nhooyr.io/websocket v1.8.7 h1:usjR2uOr/zjjkVMy0lW+PPohFok7PCow5sDjLgX4P4g=
 nhooyr.io/websocket v1.8.7/go.mod h1:B70DZP8IakI65RVQ51MsWP/8jndNma26DVA/nFSCgW0=
-oss.terrastruct.com/util-go v0.0.0-20230303172031-56bcfcdf965d h1:NytIu7ehF8FL5mb8Rw3yTTa3eyTu3xpi3cUejeAv1cE=
-oss.terrastruct.com/util-go v0.0.0-20230303172031-56bcfcdf965d/go.mod h1:eMWv0sOtD9T2RUl90DLWfuShZCYp4NrsqNpI8eqO6U4=
+oss.terrastruct.com/util-go v0.0.0-20230303204624-090ad7923dcb h1:Zgb7Wf7mTpXmIiYv0bIJ8IULcdJVIxiRihnUvDP9YMQ=
+oss.terrastruct.com/util-go v0.0.0-20230303204624-090ad7923dcb/go.mod h1:eMWv0sOtD9T2RUl90DLWfuShZCYp4NrsqNpI8eqO6U4=
 rsc.io/pdf v0.1.1 h1:k1MczvYDUvJBe93bYd7wrZLLUEcLZAuF824/I4e5Xr4=