Create new snake_case_converter.

Add a conversion function from - to _ and add unit test.
Signed-off-by: Maggie Zhou <mzhou@slack-corp.com>

go/stats/kebab_case_converter.go

@@ -22,32 +22,6 @@ import (
 	"sync"
 )
 
-// GetSnakeName calls toSnakeName on the passed in string. It produces
-// a snake-cased name from the provided camel-cased name.
-// It memoizes the transformation and returns the stored result if available.
-func GetSnakeName(name string) string {
-	return toSnakeCase(name)
-}
-
-// toSnakeCase produces a monitoring compliant name from the original.
-// For systems (like Prometheus) that ask for snake-case names.
-// It converts CamelCase to camel_case, and CAMEL_CASE to camel_case.
-// For numbers, it converts 0.5 to v0_5.
-func toSnakeCase(name string) (hyphenated string) {
-	memoizer.Lock()
-	defer memoizer.Unlock()
-	if hyphenated = memoizer.memo[name]; hyphenated != "" {
-		return hyphenated
-	}
-	hyphenated = name
-	for _, converter := range snakeConverters {
-		hyphenated = converter.re.ReplaceAllString(hyphenated, converter.repl)
-	}
-	hyphenated = strings.ToLower(hyphenated)
-	memoizer.memo[name] = hyphenated
-	return
-}
-
 // toKebabCase produces a monitoring compliant name from the
 // original. It converts CamelCase to camel-case,
 // and CAMEL_CASE to camel-case. For numbers, it
@@ -79,17 +53,6 @@ var kebabConverters = []struct {
 	{regexp.MustCompile("\\."), "_"},
 }
 
-var snakeConverters = []struct {
-	re   *regexp.Regexp
-	repl string
-}{
-	// example: LC -> L_C (e.g. CamelCase -> Camel_Case).
-	{regexp.MustCompile("([a-z])([A-Z])"), "${1}_${2}"},
-	// example: CCa -> C_Ca (e.g. CCamel -> C_Camel).
-	{regexp.MustCompile("([A-Z])([A-Z][a-z])"), "${1}_${2}"},
-	{regexp.MustCompile("\\."), "_"},
-}
-
 var memoizer = memoizerType{
 	memo: make(map[string]string),
 }

go/stats/snake_case_converter.go

@@ -0,0 +1,64 @@
+/*
+Copyright 2018 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package stats
+
+import (
+	"regexp"
+	"strings"
+)
+
+// GetSnakeName calls toSnakeName on the passed in string. It produces
+// a snake-cased name from the provided camel-cased name.
+// It memoizes the transformation and returns the stored result if available.
+func GetSnakeName(name string) string {
+	return toSnakeCase(name)
+}
+
+// toSnakeCase produces a monitoring compliant name from the original.
+// For systems (like Prometheus) that ask for snake-case names.
+// It converts CamelCase to camel_case, and CAMEL_CASE to camel_case.
+// For numbers, it converts 0.5 to v0_5.
+func toSnakeCase(name string) (hyphenated string) {
+	snakeMemoizer.Lock()
+	defer snakeMemoizer.Unlock()
+	if hyphenated = snakeMemoizer.memo[name]; hyphenated != "" {
+		return hyphenated
+	}
+	hyphenated = name
+	for _, converter := range snakeConverters {
+		hyphenated = converter.re.ReplaceAllString(hyphenated, converter.repl)
+	}
+	hyphenated = strings.ToLower(hyphenated)
+	snakeMemoizer.memo[name] = hyphenated
+	return
+}
+
+var snakeConverters = []struct {
+	re   *regexp.Regexp
+	repl string
+}{
+	// example: LC -> L_C (e.g. CamelCase -> Camel_Case).
+	{regexp.MustCompile("([a-z])([A-Z])"), "${1}_${2}"},
+	// example: CCa -> C_Ca (e.g. CCamel -> C_Camel).
+	{regexp.MustCompile("([A-Z])([A-Z][a-z])"), "${1}_${2}"},
+	{regexp.MustCompile("\\."), "_"},
+	{regexp.MustCompile("-"), "_"},
+}
+
+var snakeMemoizer = memoizerType{
+	memo: make(map[string]string),
+}

go/stats/snake_case_converter_test.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2018 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package stats
+
+import "testing"
+
+func TestToSnakeCase(t *testing.T) {
+	var snakeCaseTest = []struct{ input, output string }{
+		{"Camel", "camel"},
+		{"Camel", "camel"},
+		{"CamelCase", "camel_case"},
+		{"CamelCaseAgain", "camel_case_again"},
+		{"CCamel", "c_camel"},
+		{"CCCamel", "cc_camel"},
+		{"CAMEL_CASE", "camel_case"},
+		{"camel-case", "camel_case"},
+		{"0", "0"},
+		{"0.0", "0_0"},
+		{"JSON", "json"},
+	}
+
+	for _, tt := range snakeCaseTest {
+		if got, want := toSnakeCase(tt.input), tt.output; got != want {
+			t.Errorf("want '%s', got '%s'", want, got)
+		}
+	}
+}
+
+func TestSnakeMemoize(t *testing.T) {
+	key := "Test"
+	if snakeMemoizer.memo[key] != "" {
+		t.Errorf("want '', got '%s'", snakeMemoizer.memo[key])
+	}
+	toSnakeCase(key)
+	if snakeMemoizer.memo[key] != "test" {
+		t.Errorf("want 'test', got '%s'", snakeMemoizer.memo[key])
+	}
+}