better round trip for dots

model/metric.go

@@ -305,7 +305,7 @@ func EscapeName(name string, scheme EscapingScheme) string {
 			} else if isValidLegacyRune(b, i) {
 				escaped.WriteRune(b)
 			} else {
-				escaped.WriteRune('_')
+				escaped.WriteString("__")
 			}
 		}
 		return escaped.String()

model/metric_test.go

@@ -281,26 +281,26 @@ func TestEscapeName(t *testing.T) {
 			name:                  "name with spaces and emoji",
 			input:                 "label with 😱",
 			expectedUnderscores:   "label_with__",
-			expectedDots:          "label_with__",
-			expectedUnescapedDots: "label_with_",
+			expectedDots:          "label__with____",
+			expectedUnescapedDots: "label_with__",
 			expectedValue:         "U__label_20_with_20__1f631_",
 		},
 		{
 			name:                "name with unicode characters > 0x100",
 			input:               "花火",
 			expectedUnderscores: "__",
-			expectedDots:        "__",
+			expectedDots:        "____",
 			// Dots-replacement does not know the difference between two replaced
 			// characters and a single underscore.
-			expectedUnescapedDots: "_",
+			expectedUnescapedDots: "__",
 			expectedValue:         "U___82b1__706b_",
 		},
 		{
 			name:                  "name with spaces and edge-case value",
 			input:                 "label with \u0100",
 			expectedUnderscores:   "label_with__",
-			expectedDots:          "label_with__",
-			expectedUnescapedDots: "label_with_",
+			expectedDots:          "label__with____",
+			expectedUnescapedDots: "label_with__",
 			expectedValue:         "U__label_20_with_20__100_",
 		},
 	}