Add more test cases

.github/workflows/build.yml

@@ -24,7 +24,7 @@ jobs:
         run: go build -v ./...
 
       - name: Test
-        run: go test -race -cover -coverprofile="coverage.txt" -covermode=atomic ./...
+        run: go test -race -cover -coverprofile="coverage.out" -covermode=atomic ./...
 
-      - name: Coverage
+      - name: Codecov
         uses: codecov/codecov-action@v1

errors_test.go

@@ -0,0 +1,60 @@
+package gonfig
+
+import (
+	"errors"
+	"reflect"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestInvalidInputError_Error(t *testing.T) {
+	var i interface{}
+	var s struct{}
+	var sp *struct{}
+	num := 2
+
+	tests := []struct {
+		input    interface{}
+		expected string
+	}{
+		{
+			input:    nil,
+			expected: "<nil>",
+		},
+		{
+			input:    i,
+			expected: "<nil>",
+		},
+		{
+			input:    s,
+			expected: "non-pointer type",
+		},
+		{
+			input:    sp,
+			expected: "nil pointer",
+		},
+		{
+			input:    &num,
+			expected: "non-struct type",
+		},
+	}
+
+	for _, tc := range tests {
+		ie := InvalidInputError{
+			Value: reflect.ValueOf(tc.input),
+		}
+
+		assert.EqualError(t, &ie, "gonfig: invalid input: "+tc.expected)
+	}
+}
+
+func TestConfigErrors_Error(t *testing.T) {
+	ce := ConfigErrors{
+		errors.New("first"),
+		errors.New("second"),
+		errors.New("third"),
+	}
+
+	assert.EqualError(t, ce, "gonfig:\n  * first\n  * second\n  * third")
+}

testdata/config.yml

@@ -1,4 +1,9 @@
+foo:
+  &foo
+  bar: baz
+
 config:
   host: golang.org
+  <<: *foo
 
 custom_key: custom