mount-utils: add isMountPointMatch test and benchmark

Add some test cases for isMountPointMatch, to prepare for its rework.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

staging/src/k8s.io/mount-utils/mount_helper_unix_test.go

@@ -332,3 +332,35 @@ func TestBadParseMountInfo(t *testing.T) {
 		}
 	}
 }
+
+func testIsMountPointMatch(t testing.TB) {
+	mpCases := []struct {
+		mp, dir string
+		res     bool
+	}{
+		{"", "", true},
+		{"/", "/", true},
+		{"/some/path", "/some/path", true},
+		{"/a/different/kind/of/path\\040(deleted)", "/a/different/kind/of/path", true},
+		{"one", "two", false},
+		{"a somewhat long path that ends with A", "a somewhat long path that ends with B", false},
+	}
+
+	for _, tc := range mpCases {
+		mp := MountPoint{Path: tc.mp}
+		res := isMountPointMatch(mp, tc.dir)
+		if res != tc.res {
+			t.Errorf("mp: %q, dir: %q, expected %v, got %v", tc.mp, tc.dir, tc.res, res)
+		}
+	}
+}
+
+func TestIsMountPointMatch(t *testing.T) {
+	testIsMountPointMatch(t)
+}
+
+func BenchmarkIsMountPointMatch(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		testIsMountPointMatch(b)
+	}
+}