Remove defer and test parseRateLimiter (#4540)

Remove defer (#3) and add three tests to check if parsing ratelimiting env vars works correctly

api/client.go

@@ -364,12 +364,6 @@ func NewClient(c *Config) (*Client, error) {
 		c = def
 	}
 
-	// Check to see if the Limiter has been set.
-	// If is has not been set, then set it to have no limit.
-	if c.Limiter == nil {
-		c.Limiter = rate.NewLimiter(rate.Inf, 0)
-	}
-
 	c.modifyLock.Lock()
 	defer c.modifyLock.Unlock()
 
@@ -596,7 +590,10 @@ func (c *Client) NewRequest(method, requestPath string) *Request {
 // a Vault server not configured with this client. This is an advanced operation
 // that generally won't need to be called externally.
 func (c *Client) RawRequest(r *Request) (*Response, error) {
-	defer c.config.Limiter.Wait(context.Background())
+	if c.config.Limiter != nil {
+		c.config.Limiter.Wait(context.Background())
+	}
+
 	c.modifyLock.RLock()
 	c.config.modifyLock.RLock()
 	defer c.config.modifyLock.RUnlock()

api/client_test.go

@@ -196,6 +196,48 @@ func TestClientEnvSettings(t *testing.T) {
 	}
 }
 
+func TestParsingRateAndBurst(t *testing.T) {
+	var (
+		correctFormat                    = "400:400"
+		observedRate, observedBurst, err = parseRateLimit(correctFormat)
+		expectedRate, expectedBurst      = float(400), 400
+	)
+	if err != nil {
+		t.Error(err)
+	}
+	if expectedRate != observedRate {
+		t.Errorf("Expected rate %v but found %v", expectedRate, observedRate)
+	}
+	if expectedBurst != observedBurst {
+		t.Errorf("Expected burst %v but found %v", expectedRate, observedRate)
+	}
+}
+
+func TestParsingRateOnly(t *testing.T) {
+	var (
+		correctFormat                    = "400"
+		observedRate, observedBurst, err = parseRateLimit(correctFormat)
+		expectedRate, expectedBurst      = float(400), 400
+	)
+	if err != nil {
+		t.Error(err)
+	}
+	if expectedRate != observedRate {
+		t.Errorf("Expected rate %v but found %v", expectedRate, observedRate)
+	}
+	if expectedBurst != observedBurst {
+		t.Errorf("Expected burst %v but found %v", expectedRate, observedRate)
+	}
+}
+
+func TestParsingErrorCase(t *testing.T) {
+	var incorrectFormat = "foobar"
+	var _, _, err = parseRateLimit(correctFormat)
+	if err == nil {
+		t.Error("Expected error, found no error")
+	}
+}
+
 func TestClientTimeoutSetting(t *testing.T) {
 	oldClientTimeout := os.Getenv(EnvVaultClientTimeout)
 	os.Setenv(EnvVaultClientTimeout, "10")