os: implement and test os.MkdirTemp

src/os/tempfile_test.go

@@ -8,12 +8,19 @@ import (
 	"errors"
 	. "os"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"testing"
 )
 
 func TestCreateTemp(t *testing.T) {
-	nonexistentDir := filepath.Join("_also_not_exists_", "_not_exists_")
+	dir, err := MkdirTemp("", "TestCreateTempBadDir")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer RemoveAll(dir)
+
+	nonexistentDir := filepath.Join(dir, "_not_exists_")
 	f, err := CreateTemp(nonexistentDir, "foo")
 	if f != nil || err == nil {
 		t.Errorf("CreateTemp(%q, `foo`) = %v, %v", nonexistentDir, f, err)
@@ -43,7 +50,11 @@ func TestCreateTempPattern(t *testing.T) {
 }
 
 func TestCreateTempBadPattern(t *testing.T) {
-	tmpDir := TempDir()
+	tmpDir, err := MkdirTemp("", t.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer RemoveAll(tmpDir)
 
 	const sep = string(PathSeparator)
 	tests := []struct {
@@ -77,3 +88,106 @@ func TestCreateTempBadPattern(t *testing.T) {
 		})
 	}
 }
+
+func TestMkdirTemp(t *testing.T) {
+	name, err := MkdirTemp("/_not_exists_", "foo")
+	if name != "" || err == nil {
+		t.Errorf("MkdirTemp(`/_not_exists_`, `foo`) = %v, %v", name, err)
+	}
+
+	tests := []struct {
+		pattern                string
+		wantPrefix, wantSuffix string
+	}{
+		{"tempfile_test", "tempfile_test", ""},
+		{"tempfile_test*", "tempfile_test", ""},
+		{"tempfile_test*xyz", "tempfile_test", "xyz"},
+	}
+
+	dir := filepath.Clean(TempDir())
+
+	runTestMkdirTemp := func(t *testing.T, pattern, wantRePat string) {
+		name, err := MkdirTemp(dir, pattern)
+		if name == "" || err != nil {
+			t.Fatalf("MkdirTemp(dir, `tempfile_test`) = %v, %v", name, err)
+		}
+		defer Remove(name)
+
+		re := regexp.MustCompile(wantRePat)
+		if !re.MatchString(name) {
+			t.Errorf("MkdirTemp(%q, %q) created bad name\n\t%q\ndid not match pattern\n\t%q", dir, pattern, name, wantRePat)
+		}
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.pattern, func(t *testing.T) {
+			wantRePat := "^" + regexp.QuoteMeta(filepath.Join(dir, tt.wantPrefix)) + "[0-9]+" + regexp.QuoteMeta(tt.wantSuffix) + "$"
+			runTestMkdirTemp(t, tt.pattern, wantRePat)
+		})
+	}
+
+	// Separately testing "*xyz" (which has no prefix). That is when constructing the
+	// pattern to assert on, as in the previous loop, using filepath.Join for an empty
+	// prefix filepath.Join(dir, ""), produces the pattern:
+	//     ^<DIR>[0-9]+xyz$
+	// yet we just want to match
+	//     "^<DIR>/[0-9]+xyz"
+	t.Run("*xyz", func(t *testing.T) {
+		wantRePat := "^" + regexp.QuoteMeta(filepath.Join(dir)) + regexp.QuoteMeta(string(filepath.Separator)) + "[0-9]+xyz$"
+		runTestMkdirTemp(t, "*xyz", wantRePat)
+	})
+}
+
+// test that we return a nice error message if the dir argument to TempDir doesn't
+// exist (or that it's empty and TempDir doesn't exist)
+func TestMkdirTempBadDir(t *testing.T) {
+	dir, err := MkdirTemp("", "MkdirTempBadDir")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer RemoveAll(dir)
+
+	badDir := filepath.Join(dir, "not-exist")
+	_, err = MkdirTemp(badDir, "foo")
+	// TODO: when we drop support for go 1.15, PathError should move to fs
+	if pe, ok := err.(*PathError); !ok || !IsNotExist(err) || pe.Path != badDir {
+		t.Errorf("TempDir error = %#v; want PathError for path %q satisifying IsNotExist", err, badDir)
+	}
+}
+
+func TestMkdirTempBadPattern(t *testing.T) {
+	tmpDir, err := MkdirTemp("", t.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer RemoveAll(tmpDir)
+
+	const sep = string(PathSeparator)
+	tests := []struct {
+		pattern string
+		wantErr bool
+	}{
+		{"ioutil*test", false},
+		{"tempfile_test*foo", false},
+		{"tempfile_test" + sep + "foo", true},
+		{"tempfile_test*" + sep + "foo", true},
+		{"tempfile_test" + sep + "*foo", true},
+		{sep + "tempfile_test" + sep + "*foo", true},
+		{"tempfile_test*foo" + sep, true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.pattern, func(t *testing.T) {
+			_, err := MkdirTemp(tmpDir, tt.pattern)
+			if tt.wantErr {
+				if err == nil {
+					t.Errorf("MkdirTemp(..., %#q) succeeded, expected error", tt.pattern)
+				}
+				if !errors.Is(err, ErrPatternHasSeparator) {
+					t.Errorf("MkdirTemp(..., %#q): %v, expected ErrPatternHasSeparator", tt.pattern, err)
+				}
+			} else if err != nil {
+				t.Errorf("MkdirTemp(..., %#q): %v", tt.pattern, err)
+			}
+		})
+	}
+}