diff --git a/config/config.go b/config/config.go
index e2c08e4e..d430c2b3 100644
--- a/config/config.go
+++ b/config/config.go
@@ -259,13 +259,13 @@ func (c *Config) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	// The root route must not have any matchers as it is the fallback node
 	// for all alerts.
 	if c.Route == nil {
-		return fmt.Errorf("No routes provided")
+		return fmt.Errorf("no routes provided")
 	}
 	if len(c.Route.Receiver) == 0 {
-		return fmt.Errorf("Root route must specify a default receiver")
+		return fmt.Errorf("root route must specify a default receiver")
 	}
 	if len(c.Route.Match) > 0 || len(c.Route.MatchRE) > 0 {
-		return fmt.Errorf("Root route must not have any matchers")
+		return fmt.Errorf("root route must not have any matchers")
 	}
 
 	// Validate that all receivers used in the routing tree are defined.
@@ -283,7 +283,7 @@ func checkReceiver(r *Route, receivers map[string]struct{}) error {
 		return nil
 	}
 	if _, ok := receivers[r.Receiver]; !ok {
-		return fmt.Errorf("Undefined receiver %q used in route", r.Receiver)
+		return fmt.Errorf("undefined receiver %q used in route", r.Receiver)
 	}
 	for _, sr := range r.Routes {
 		if err := checkReceiver(sr, receivers); err != nil {
diff --git a/config/config_test.go b/config/config_test.go
index 9c71160f..67cb6e6c 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -26,16 +26,12 @@ import (
 	"gopkg.in/yaml.v2"
 )
 
-func TestDefaultReceiverExists(t *testing.T) {
-	in := `
-route:
-   group_wait: 30s
-`
+func TestLoadEmptyString(t *testing.T) {
 
-	conf := &Config{}
-	err := yaml.Unmarshal([]byte(in), conf)
+	var in string
+	_, err := Load(in)
 
-	expected := "Root route must specify a default receiver"
+	expected := "no route provided in config"
 
 	if err == nil {
 		t.Fatalf("no error returned, expected:\n%v", expected)
@@ -45,6 +41,149 @@ route:
 	}
 }
 
+func TestDefaultReceiverExists(t *testing.T) {
+	in := `
+route:
+   group_wait: 30s
+`
+	conf := &Config{}
+	err := yaml.Unmarshal([]byte(in), conf)
+
+	expected := "root route must specify a default receiver"
+
+	if err == nil {
+		t.Fatalf("no error returned, expected:\n%v", expected)
+	}
+	if err.Error() != expected {
+		t.Errorf("\nexpected:\n%v\ngot:\n%v", expected, err.Error())
+	}
+}
+
+func TestReceiverNameIsUnique(t *testing.T) {
+	in := `
+route:
+    receiver: team-X
+
+receivers:
+- name: 'team-X'
+- name: 'team-X'
+`
+	_, err := Load(in)
+
+	expected := "notification config name \"team-X\" is not unique"
+
+	if err == nil {
+		t.Fatalf("no error returned, expeceted:\n%q", expected)
+	}
+	if err.Error() != expected {
+		t.Errorf("\nexpected:\n%q\ngot:\n%q", expected, err.Error())
+	}
+
+}
+
+func TestReceiverExists(t *testing.T) {
+	in := `
+route:
+    receiver: team-X
+
+receivers:
+- name: 'team-Y'
+`
+	_, err := Load(in)
+
+	expected := "undefined receiver \"team-X\" used in route"
+
+	if err == nil {
+		t.Fatalf("no error returned, expeceted:\n%q", expected)
+	}
+	if err.Error() != expected {
+		t.Errorf("\nexpected:\n%q\ngot:\n%q", expected, err.Error())
+	}
+
+}
+
+func TestReceiverHasName(t *testing.T) {
+	in := `
+route:
+
+receivers:
+- name: ''
+`
+	_, err := Load(in)
+
+	expected := "missing name in receiver"
+
+	if err == nil {
+		t.Fatalf("no error returned, expeceted:\n%q", expected)
+	}
+	if err.Error() != expected {
+		t.Errorf("\nexpected:\n%q\ngot:\n%q", expected, err.Error())
+	}
+
+}
+
+func TestGroupByHasNoDuplicatedLabels(t *testing.T) {
+	in := `
+route:
+  group_by: ['alertname', 'cluster', 'service', 'cluster']
+
+receivers:
+- name: 'team-X-mails'
+`
+	_, err := Load(in)
+
+	expected := "duplicated label \"cluster\" in group_by"
+
+	if err == nil {
+		t.Fatalf("no error returned, expeceted:\n%q", expected)
+	}
+	if err.Error() != expected {
+		t.Errorf("\nexpected:\n%q\ngot:\n%q", expected, err.Error())
+	}
+
+}
+
+func TestRootRouteExists(t *testing.T) {
+	in := `
+receivers:
+- name: 'team-X-mails'
+`
+	_, err := Load(in)
+
+	expected := "no routes provided"
+
+	if err == nil {
+		t.Fatalf("no error returned, expeceted:\n%q", expected)
+	}
+	if err.Error() != expected {
+		t.Errorf("\nexpected:\n%q\ngot:\n%q", expected, err.Error())
+	}
+
+}
+
+func TestRootRouteHasNoMatcher(t *testing.T) {
+	in := `
+route:
+  receiver: 'team-X'
+  match:
+    severity: critical
+
+receivers:
+- name: 'team-X'
+`
+	_, err := Load(in)
+
+	expected := "root route must not have any matchers"
+
+	if err == nil {
+		t.Fatalf("no error returned, expeceted:\n%q", expected)
+	}
+	if err.Error() != expected {
+		t.Errorf("\nexpected:\n%q\ngot:\n%q", expected, err.Error())
+	}
+
+}
+
 func TestContinueErrorInRouteRoot(t *testing.T) {
 	in := `
 route:
@@ -54,7 +193,6 @@ route:
 receivers:
 - name: 'team-X-mails'
 `
-
 	_, err := Load(in)
 
 	expected := "cannot have continue in root route"