util/cmpver: add Less/LessEq helper funcs

Updates tailscale/corp#17199

Signed-off-by: Paul Scott <paul@tailscale.com>

util/cmpver/version.go

@@ -24,6 +24,20 @@ import (
 	"strings"
 )
 
+// Less reports whether v1 is less than v2.
+//
+// Note that "12" is less than "12.0".
+func Less(v1, v2 string) bool {
+	return Compare(v1, v2) < 0
+}
+
+// LessEq reports whether v1 is less than or equal to v2.
+//
+// Note that "12" is less than "12.0".
+func LessEq(v1, v2 string) bool {
+	return Compare(v1, v2) <= 0
+}
+
 func isnum(r rune) bool {
 	return r >= '0' && r <= '9'
 }
@@ -32,9 +46,12 @@ func notnum(r rune) bool {
 	return !isnum(r)
 }
 
-// Compare returns an integer comparing two strings as version
-// numbers. The result will be 0 if v1==v2, -1 if v1 < v2, and +1 if
-// v1 > v2.
+// Compare returns an integer comparing two strings as version numbers.
+// The result will be -1, 0, or 1 representing the sign of v1 - v2:
+//
+//	Compare(v1, v2)  < 0  if v1  < v2
+//	                == 0  if v1 == v2
+//	                 > 0  if v1  > v2
 func Compare(v1, v2 string) int {
 	var (
 		f1, f2 string

util/cmpver/version_test.go

@@ -163,16 +163,31 @@ func TestCompare(t *testing.T) {
 		t.Run(test.name, func(t *testing.T) {
 			got := cmpver.Compare(test.v1, test.v2)
 			if got != test.want {
-				t.Errorf("Compare(%v, %v) = %v, want %v", test.v1, test.v2, got, test.want)
+				t.Errorf("Compare(%q, %q) = %v, want %v", test.v1, test.v2, got, test.want)
 			}
+
 			// Reversing the comparison should reverse the outcome.
 			got2 := cmpver.Compare(test.v2, test.v1)
 			if got2 != -test.want {
-				t.Errorf("Compare(%v, %v) = %v, want %v", test.v2, test.v1, got2, -test.want)
+				t.Errorf("Compare(%q, %q) = %v, want %v", test.v2, test.v1, got2, -test.want)
 			}
+
+			if got, want := cmpver.Less(test.v1, test.v2), test.want < 0; got != want {
+				t.Errorf("Less(%q, %q) = %v, want %v", test.v1, test.v2, got, want)
+			}
+			if got, want := cmpver.Less(test.v2, test.v1), test.want > 0; got != want {
+				t.Errorf("Less(%q, %q) = %v, want %v", test.v2, test.v1, got, want)
+			}
+			if got, want := cmpver.LessEq(test.v1, test.v2), test.want <= 0; got != want {
+				t.Errorf("LessEq(%q, %q) = %v, want %v", test.v1, test.v2, got, want)
+			}
+			if got, want := cmpver.LessEq(test.v2, test.v1), test.want >= 0; got != want {
+				t.Errorf("LessEq(%q, %q) = %v, want %v", test.v2, test.v1, got, want)
+			}
+
 			// Check that version comparison does not allocate.
 			if n := testing.AllocsPerRun(100, func() { cmpver.Compare(test.v1, test.v2) }); n > 0 {
-				t.Errorf("Compare(%v, %v) got %v allocs per run", test.v1, test.v2, n)
+				t.Errorf("Compare(%q, %q) got %v allocs per run", test.v1, test.v2, n)
 			}
 		})
 	}