Test internal/drawstate and the module packages each package may import

builtins_test.go

@@ -105,7 +105,7 @@ func TestBuiltinChecksums(t *testing.T) {
 
 // TestBuiltinSeqPerGenerator pins seq's contract: a counter from 1, advancing on
 // each call, named counters independent, and the whole thing scoped to one
-// generatorState so a fresh Generator restarts at 1.
+// draw state so a fresh Generator restarts at 1.
 func TestBuiltinSeqPerGenerator(t *testing.T) {
 	f := engine(1)
 	for i := 1; i <= 5; i++ {

fejkdata_test.go

@@ -7,6 +7,8 @@ import (
 	"strings"
 	"testing"
 	"testing/fstest"
+
+	"github.com/larvit/fejkdata/internal/drawstate"
 )
 
 // newGenerator creates a generator over a single data directory, failing on
@@ -96,11 +98,7 @@ func fakeTemplate(t *testing.T, f *Generator, s string) string {
 
 // engine builds a seeded generator with no loaded categories, for rendering tests.
 func engine(seed uint64) *Generator {
-	s, err := newRand(seed, true)
-	if err != nil {
-		panic(err)
-	}
-	return &Generator{rand: s}
+	return &Generator{draws: drawstate.New(seed)}
 }
 
 // parse unmarshals a JSON template fragment into its dynamic form.
@@ -135,5 +133,5 @@ func compiled(t *testing.T, s string) node {
 
 func mustRender(t *testing.T, f *Generator, s string) string {
 	t.Helper()
-	return renderOnce(f.rand, compiled(t, s))
+	return renderOnce(f.draws, compiled(t, s))
 }

imports_test.go

@@ -0,0 +1,66 @@
+package fejkdata
+
+import (
+	"errors"
+	"go/build"
+	"io/fs"
+	"path/filepath"
+	"slices"
+	"strings"
+	"testing"
+)
+
+// TestPackageImports holds each package in the module to the module packages it may import.
+func TestPackageImports(t *testing.T) {
+	const module = "github.com/larvit/fejkdata"
+	allowed := map[string][]string{
+		".":                  {"internal/drawstate"},
+		"cmd/fejkdata":       {"."},
+		"internal/drawstate": nil,
+	}
+	seen := map[string]bool{}
+	err := filepath.WalkDir(".", func(dir string, d fs.DirEntry, err error) error {
+		if err != nil || !d.IsDir() {
+			return err
+		}
+		if dir != "." && (strings.HasPrefix(d.Name(), ".") || d.Name() == "testdata") {
+			return filepath.SkipDir
+		}
+		pkg, err := build.ImportDir(dir, 0)
+		var noGo *build.NoGoError
+		if errors.As(err, &noGo) {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+		dir = filepath.ToSlash(dir)
+		seen[dir] = true
+		may, listed := allowed[dir]
+		if !listed {
+			t.Errorf("package %s is not listed: add the module packages it may import", dir)
+			return nil
+		}
+		for _, imp := range slices.Concat(pkg.Imports, pkg.TestImports, pkg.XTestImports) {
+			if imp != module && !strings.HasPrefix(imp, module+"/") {
+				continue
+			}
+			rel := strings.TrimPrefix(strings.TrimPrefix(imp, module), "/")
+			if rel == "" {
+				rel = "."
+			}
+			if rel != dir && !slices.Contains(may, rel) {
+				t.Errorf("package %s imports %s, which its list does not allow", dir, rel)
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for dir := range allowed {
+		if !seen[dir] {
+			t.Errorf("listed package %s does not exist", dir)
+		}
+	}
+}

internal/drawstate/drawstate_test.go

@@ -0,0 +1,40 @@
+package drawstate
+
+import "testing"
+
+func TestOneSeedDrawsOneSequence(t *testing.T) {
+	a, b := New(42), New(42)
+	for i := 0; i < 50; i++ {
+		if x, y := a.Uint64(), b.Uint64(); x != y {
+			t.Fatalf("seed 42 diverged at draw %d: %d != %d", i, x, y)
+		}
+	}
+}
+
+func TestTwoSeedsDrawTwoSequences(t *testing.T) {
+	a, b := New(1), New(2)
+	for i := 0; i < 50; i++ {
+		if a.Uint64() != b.Uint64() {
+			return
+		}
+	}
+	t.Fatal("seeds 1 and 2 drew identical sequences")
+}
+
+func TestCountersCountFromOneEach(t *testing.T) {
+	s := New(1)
+	for want := uint64(1); want <= 3; want++ {
+		if got := s.Next(""); got != want {
+			t.Fatalf("Next(\"\") = %d, want %d", got, want)
+		}
+	}
+	if got := s.Next("orders"); got != 1 {
+		t.Fatalf("Next(orders) = %d, want its own count from 1", got)
+	}
+	if got := s.Next(""); got != 4 {
+		t.Fatalf("Next(\"\") after Next(orders) = %d, want 4", got)
+	}
+	if got := New(1).Next(""); got != 1 {
+		t.Fatalf("a new state's Next = %d, want 1", got)
+	}
+}

path_test.go

@@ -35,7 +35,7 @@ func TestDrawStepsPanicsOnAStepItsNodeLacks(t *testing.T) {
 			t.Errorf("drawSteps(plain, f) recovered %v, want a panic naming the missing field", r)
 		}
 	}()
-	drawSteps(engine(1).rand, compiled(t, `"plain"`), []pathStep{{kind: stepField, name: "f"}}, &pinSet{}, nil, nil)
+	drawSteps(engine(1).draws, compiled(t, `"plain"`), []pathStep{{kind: stepField, name: "f"}}, &pinSet{}, nil, nil)
 }
 
 func TestDeepDottedPath(t *testing.T) {

render_test.go

@@ -43,7 +43,7 @@ func TestGrowIsALowerBound(t *testing.T) {
 		}
 		for i := 0; i < 50; i++ {
 			var frames frameStack
-			if got := len(expand(f.rand, tmpl, renderScope{frames: &frames})); got < tmpl.compiled.grow {
+			if got := len(expand(f.draws, tmpl, renderScope{frames: &frames})); got < tmpl.compiled.grow {
 				t.Errorf("format %q: expand emitted %d bytes, below grow %d", format, got, tmpl.compiled.grow)
 			}
 		}
@@ -113,7 +113,7 @@ func TestNodeSwitchesHandleEveryKind(t *testing.T) {
 		"prove":       func(n node) { (&valueProof{}).prove(n) },
 		"render": func(n node) {
 			var frames frameStack
-			render(engine(1).rand, n, renderScope{frames: &frames, row: renderedRow{tbl, 0}})
+			render(engine(1).draws, n, renderScope{frames: &frames, row: renderedRow{tbl, 0}})
 		},
 		"renderEdges": func(n node) { renderEdges(n) },
 		"stepInto":    func(n node) { _, _ = stepInto(n, "x") },