fix: ftltest config: use ConfigPaths with envar fallback (#1543)

Fixes #1502.

Adds tests to ensure we're correctly falling back to the config in
`FTL_CONFIG` and to `ftl-project.toml` in the gitroot.

go-runtime/ftl/ftltest/ftltest.go

@@ -16,6 +16,7 @@ import (
 
 	"github.com/TBD54566975/ftl/backend/schema"
 	cf "github.com/TBD54566975/ftl/common/configuration"
+	pc "github.com/TBD54566975/ftl/common/projectconfig"
 	"github.com/TBD54566975/ftl/go-runtime/ftl"
 	"github.com/TBD54566975/ftl/go-runtime/ftl/reflection"
 	"github.com/TBD54566975/ftl/internal/log"
@@ -59,7 +60,8 @@ func Context(options ...Option) context.Context {
 // WithProjectFiles loads config and secrets from a project file
 //
 // Takes a list of paths to project files. If multiple paths are provided, they are loaded in order, with later files taking precedence.
-// If no paths are provided, the list is inferred from the FTL_CONFIG environment variable. If that is not found, an error is returned.
+// If no paths are provided, the list is inferred from the FTL_CONFIG environment variable. If that is not found, the ftl-project.toml
+// file in the git root is used. If ftl-project.toml is not found, no project files are loaded.
 //
 // To be used when setting up a context for a test:
 // ctx := ftltest.Context(
@@ -73,10 +75,11 @@ func WithProjectFiles(paths ...string) Option {
 	var preprocessingErr error
 	if len(paths) == 0 {
 		envValue, ok := os.LookupEnv("FTL_CONFIG")
-		if !ok {
-			preprocessingErr = fmt.Errorf("loading project files: no path provided and FTL_CONFIG environment variable not set")
+		if ok {
+			paths = strings.Split(envValue, ",")
+		} else {
+			paths = pc.ConfigPaths(paths)
 		}
-		paths = strings.Split(envValue, ",")
 	}
 	paths = slices.Map(paths, func(p string) string {
 		path, err := filepath.Abs(p)

integration/testdata/go/wrapped/ftl-project.toml

@@ -0,0 +1,12 @@
+ftl-min-version = ""
+
+[global]
+  [global.configuration]
+    config = "inline://ImJhemJheiI"
+  [global.secrets]
+    secret = "inline://ImJhemJheiI"
+
+[executables]
+  ftl = ""
+
+[commands]

integration/testdata/go/wrapped/wrapped_test.go

@@ -13,13 +13,54 @@ import (
 	"github.com/alecthomas/assert/v2"
 )
 
-func TestWrapped(t *testing.T) {
+func TestWrappedWithConfigEnvar(t *testing.T) {
 	absProjectPath1, err := filepath.Abs("ftl-project-test-1.toml")
 	assert.NoError(t, err)
 	absProjectPath2, err := filepath.Abs("ftl-project-test-2.toml")
 	assert.NoError(t, err)
 	t.Setenv("FTL_CONFIG", fmt.Sprintf("%s,%s", absProjectPath1, absProjectPath2))
 
+	for _, tt := range []struct {
+		name          string
+		options       []ftltest.Option
+		configValue   string
+		secretValue   string
+		expectedError ftl.Option[string]
+	}{
+		{
+			name: "WithProjectTomlFromEnvar",
+			options: []ftltest.Option{
+				ftltest.WithProjectFiles(),
+				ftltest.WithCallsAllowedWithinModule(),
+				ftltest.WhenVerb(time.Time, func(ctx context.Context, req time.TimeRequest) (time.TimeResponse, error) {
+					return time.TimeResponse{Time: stdtime.Date(2024, 1, 1, 0, 0, 0, 0, stdtime.UTC)}, nil
+				}),
+			},
+			configValue: "foobar",
+			secretValue: "foobar",
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			ctx := ftltest.Context(
+				tt.options...,
+			)
+			myConfig.Get(ctx)
+			resp, err := Outer(ctx)
+
+			if expected, ok := tt.expectedError.Get(); ok {
+				assert.EqualError(t, err, expected)
+				return
+			} else {
+				assert.NoError(t, err)
+			}
+			assert.Equal(t, "2024-01-01 00:00:00 +0000 UTC", resp.Output)
+			assert.Equal(t, tt.configValue, resp.Config)
+			assert.Equal(t, tt.secretValue, resp.Secret)
+		})
+	}
+}
+
+func TestWrapped(t *testing.T) {
 	for _, tt := range []struct {
 		name          string
 		options       []ftltest.Option
@@ -62,7 +103,7 @@ func TestWrapped(t *testing.T) {
 			secretValue: "shhhhh",
 		},
 		{
-			name: "WithProjectToml",
+			name: "WithProjectTomlSpecified",
 			options: []ftltest.Option{
 				ftltest.WithProjectFiles("ftl-project-test-1.toml"),
 				ftltest.WithCallsAllowedWithinModule(),
@@ -73,16 +114,16 @@ func TestWrapped(t *testing.T) {
 			configValue: "bar",
 			secretValue: "bar",
 		}, {
-			name: "WithProjectTomlFromEnvar",
+			name: "WithProjectTomlFromRoot",
 			options: []ftltest.Option{
 				ftltest.WithProjectFiles(),
 				ftltest.WithCallsAllowedWithinModule(),
 				ftltest.WhenVerb(time.Time, func(ctx context.Context, req time.TimeRequest) (time.TimeResponse, error) {
 					return time.TimeResponse{Time: stdtime.Date(2024, 1, 1, 0, 0, 0, 0, stdtime.UTC)}, nil
 				}),
 			},
-			configValue: "foobar",
-			secretValue: "foobar",
+			configValue: "bazbaz",
+			secretValue: "bazbaz",
 		},
 	} {
 		t.Run(tt.name, func(t *testing.T) {