forked from mirror/viper
Adds MergeConfig functionality
This patch adds the `MergeConfig` and `MergeInConfig` functions to
enable reading new configuration files via a merge strategy rather
than replace. For example, take the following as the base YAML for a
configuration:
hello:
pop: 37890
world:
- us
- uk
- fr
- de
Now imagine we want to read the following, new configuration data:
hello:
pop: 45000
universe:
- mw
- ad
fu: bar
Using the standard `ReadConfig` function the value returned by the
nested key `hello.world` would no longer be present after the second
configuration is read. This is because the `ReadConfig` function and
its relatives replace nested structures entirely.
The new `MergeConfig` function would produce the following config
after the second YAML snippet was merged with the first:
hello:
pop: 45000
world:
- us
- uk
- fr
- de
universe:
- mw
- ad
fu: bar
Examples showing how this works can be found in the two unit tests
named `TestMergeConfig` and `TestMergeConfigNoMerge`.
This commit is contained in:
akutz
Steve Francia
parent
c8c6312ace
commit
991d18afb2
112
viper.go
112
viper.go
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@ -901,12 +901,124 @@ func (v *Viper) ReadInConfig() error {
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return v.unmarshalReader(bytes.NewReader(file), v.config)
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}
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// MergeInConfig merges a new configuration with an existing config.
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func MergeInConfig() error { return v.MergeInConfig() }
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func (v *Viper) MergeInConfig() error {
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jww.INFO.Println("Attempting to merge in config file")
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if !stringInSlice(v.getConfigType(), SupportedExts) {
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return UnsupportedConfigError(v.getConfigType())
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}
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file, err := ioutil.ReadFile(v.getConfigFile())
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if err != nil {
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return err
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}
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return v.MergeConfig(bytes.NewReader(file))
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}
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// Viper will read a configuration file, setting existing keys to nil if the
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// key does not exist in the file.
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func ReadConfig(in io.Reader) error { return v.ReadConfig(in) }
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func (v *Viper) ReadConfig(in io.Reader) error {
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v.config = make(map[string]interface{})
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return v.unmarshalReader(in, v.config)
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}
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// MergeConfig merges a new configuration with an existing config.
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func MergeConfig(in io.Reader) error { return v.MergeConfig(in) }
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func (v *Viper) MergeConfig(in io.Reader) error {
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if v.config == nil {
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v.config = make(map[string]interface{})
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}
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cfg := make(map[string]interface{})
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if err := v.unmarshalReader(in, cfg); err != nil {
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return err
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}
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mergeMaps(cfg, v.config, nil)
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return nil
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}
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func keyExists(k string, m map[string]interface{}) string {
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lk := strings.ToLower(k)
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for mk := range m {
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lmk := strings.ToLower(mk)
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if lmk == lk {
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return mk
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}
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}
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return ""
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}
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func castToMapStringInterface(
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src map[interface{}]interface{}) map[string]interface{} {
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tgt := map[string]interface{}{}
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for k, v := range src {
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tgt[fmt.Sprintf("%v", k)] = v
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}
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return tgt
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}
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// mergeMaps merges two maps. The `itgt` parameter is for handling go-yaml's
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// insistence on parsing nested structures as `map[interface{}]interface{}`
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// instead of using a `string` as the key for nest structures beyond one level
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// deep. Both map types are supported as there is a go-yaml fork that uses
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// `map[string]interface{}` instead.
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func mergeMaps(
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src, tgt map[string]interface{}, itgt map[interface{}]interface{}) {
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for sk, sv := range src {
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tk := keyExists(sk, tgt)
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if tk == "" {
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jww.TRACE.Printf("tk=\"\", tgt[%s]=%v", sk, sv)
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tgt[sk] = sv
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if itgt != nil {
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itgt[sk] = sv
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}
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continue
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}
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tv, ok := tgt[tk]
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if !ok {
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jww.TRACE.Printf("tgt[%s] != ok, tgt[%s]=%v", tk, sk, sv)
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tgt[sk] = sv
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if itgt != nil {
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itgt[sk] = sv
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}
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continue
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}
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svType := reflect.TypeOf(sv)
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tvType := reflect.TypeOf(tv)
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if svType != tvType {
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jww.ERROR.Printf(
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"svType != tvType; key=%s, st=%v, tt=%v, sv=%v, tv=%v",
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sk, svType, tvType, sv, tv)
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continue
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}
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jww.TRACE.Printf("processing key=%s, st=%v, tt=%v, sv=%v, tv=%v",
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sk, svType, tvType, sv, tv)
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switch ttv := tv.(type) {
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case map[interface{}]interface{}:
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jww.TRACE.Printf("merging maps (must convert)")
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tsv := sv.(map[interface{}]interface{})
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ssv := castToMapStringInterface(tsv)
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stv := castToMapStringInterface(ttv)
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mergeMaps(ssv, stv, ttv)
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case map[string]interface{}:
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jww.TRACE.Printf("merging maps")
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mergeMaps(sv.(map[string]interface{}), ttv, nil)
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default:
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jww.TRACE.Printf("setting value")
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tgt[tk] = sv
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if itgt != nil {
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itgt[tk] = sv
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}
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}
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}
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}
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// func ReadBufConfig(buf *bytes.Buffer) error { return v.ReadBufConfig(buf) }
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// func (v *Viper) ReadBufConfig(buf *bytes.Buffer) error {
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// v.config = make(map[string]interface{})
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@ -737,3 +737,101 @@ func TestSub(t *testing.T) {
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assert.Equal(t, subv, (*Viper)(nil))
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}
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var yamlMergeExampleTgt = []byte(`
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hello:
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pop: 37890
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world:
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- us
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- uk
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- fr
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- de
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`)
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var yamlMergeExampleSrc = []byte(`
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hello:
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pop: 45000
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universe:
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- mw
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- ad
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fu: bar
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`)
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func TestMergeConfig(t *testing.T) {
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v := New()
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v.SetConfigType("yml")
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if err := v.ReadConfig(bytes.NewBuffer(yamlMergeExampleTgt)); err != nil {
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t.Fatal(err)
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}
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if pop := v.GetInt("hello.pop"); pop != 37890 {
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t.Fatalf("pop != 37890, = %d", pop)
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}
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if world := v.GetStringSlice("hello.world"); len(world) != 4 {
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t.Fatalf("len(world) != 4, = %d", len(world))
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}
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if fu := v.GetString("fu"); fu != "" {
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t.Fatalf("fu != \"\", = %s", fu)
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}
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if err := v.MergeConfig(bytes.NewBuffer(yamlMergeExampleSrc)); err != nil {
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t.Fatal(err)
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}
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if pop := v.GetInt("hello.pop"); pop != 45000 {
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t.Fatalf("pop != 45000, = %d", pop)
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}
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if world := v.GetStringSlice("hello.world"); len(world) != 4 {
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t.Fatalf("len(world) != 4, = %d", len(world))
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}
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if universe := v.GetStringSlice("hello.universe"); len(universe) != 2 {
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t.Fatalf("len(universe) != 2, = %d", len(universe))
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}
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if fu := v.GetString("fu"); fu != "bar" {
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t.Fatalf("fu != \"bar\", = %s", fu)
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}
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}
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func TestMergeConfigNoMerge(t *testing.T) {
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v := New()
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v.SetConfigType("yml")
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if err := v.ReadConfig(bytes.NewBuffer(yamlMergeExampleTgt)); err != nil {
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t.Fatal(err)
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}
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if pop := v.GetInt("hello.pop"); pop != 37890 {
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t.Fatalf("pop != 37890, = %d", pop)
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}
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if world := v.GetStringSlice("hello.world"); len(world) != 4 {
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t.Fatalf("len(world) != 4, = %d", len(world))
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}
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if fu := v.GetString("fu"); fu != "" {
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t.Fatalf("fu != \"\", = %s", fu)
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}
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if err := v.ReadConfig(bytes.NewBuffer(yamlMergeExampleSrc)); err != nil {
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t.Fatal(err)
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}
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if pop := v.GetInt("hello.pop"); pop != 45000 {
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t.Fatalf("pop != 45000, = %d", pop)
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}
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if world := v.GetStringSlice("hello.world"); len(world) != 0 {
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t.Fatalf("len(world) != 0, = %d", len(world))
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}
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if universe := v.GetStringSlice("hello.universe"); len(universe) != 2 {
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t.Fatalf("len(universe) != 2, = %d", len(universe))
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}
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if fu := v.GetString("fu"); fu != "bar" {
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t.Fatalf("fu != \"bar\", = %s", fu)
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}
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}
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