Internal registry for disambiguated imports, vars (#141)

* Internal registry for disambiguated imports, vars
- Move functionality in the moq package partially into
  internal/{registry,template}.
- Leverage registry to assign unique package and variable/method
  parameter names. Use import aliases if present in interface source
  package.
BREAKING CHANGE: When the interface definition does not mention the
parameter names, the field names in call info anonymous struct will be
different.
The new field names are generated using the type info (string -> s,
int -> n, chan int -> intCh, []MyType -> myTypes, map[string]int ->
stringToInt etc.).
For example, for a string parameter previously if the field name was
'In1', the new field could be 'S' or 'S1' (depends on number of
string method parameters).
* Refactor golden file tests to be table-driven
* Fix sync pkg alias handling for moq generation
* Improve, add tests (increase coverage)
* Use $.Foo in template, avoid declaring variables
$ is set to the data argument passed to Execute, that is, to the
starting value of dot.
Variables were declared to be able to refer to the parent context.
* Consistent template field formatting
* Use tabs in generated Godoc comments' example code
* Minor simplification
* go generate
* Fix conflict for generated param name of pointer type

Excellent work by @sudo-suhas.

internal/template/template.go

@@ -0,0 +1,190 @@
+package template
+
+import (
+	"io"
+	"strings"
+	"text/template"
+
+	"github.com/matryer/moq/internal/registry"
+)
+
+// Template is the Moq template. It is capable of generating the Moq
+// implementation for the given template.Data.
+type Template struct {
+	tmpl *template.Template
+}
+
+// New returns a new instance of Template.
+func New() (Template, error) {
+	tmpl, err := template.New("moq").Funcs(templateFuncs).Parse(moqTemplate)
+	if err != nil {
+		return Template{}, err
+	}
+
+	return Template{tmpl: tmpl}, nil
+}
+
+// Execute generates and writes the Moq implementation for the given
+// data.
+func (t Template) Execute(w io.Writer, data Data) error {
+	return t.tmpl.Execute(w, data)
+}
+
+// moqTemplate is the template for mocked code.
+// language=GoTemplate
+var moqTemplate = `// Code generated by moq; DO NOT EDIT.
+// github.com/matryer/moq
+
+package {{.PkgName}}
+
+import (
+{{- range .Imports}}
+	{{. | ImportStatement}}
+{{- end}}
+)
+
+{{range $i, $mock := .Mocks -}}
+
+{{- if not $.SkipEnsure -}}
+// Ensure, that {{.MockName}} does implement {{$.SrcPkgQualifier}}{{.InterfaceName}}.
+// If this is not the case, regenerate this file with moq.
+var _ {{$.SrcPkgQualifier}}{{.InterfaceName}} = &{{.MockName}}{}
+{{- end}}
+
+// {{.MockName}} is a mock implementation of {{$.SrcPkgQualifier}}{{.InterfaceName}}.
+//
+// 	func TestSomethingThatUses{{.InterfaceName}}(t *testing.T) {
+//
+// 		// make and configure a mocked {{$.SrcPkgQualifier}}{{.InterfaceName}}
+// 		mocked{{.InterfaceName}} := &{{.MockName}}{ 
+			{{- range .Methods}}
+// 			{{.Name}}Func: func({{.ArgList}}) {{.ReturnArgTypeList}} {
+// 				panic("mock out the {{.Name}} method")
+// 			},
+			{{- end}}
+// 		}
+//
+// 		// use mocked{{.InterfaceName}} in code that requires {{$.SrcPkgQualifier}}{{.InterfaceName}}
+// 		// and then make assertions.
+//
+// 	}
+type {{.MockName}} struct {
+{{- range .Methods}}
+	// {{.Name}}Func mocks the {{.Name}} method.
+	{{.Name}}Func func({{.ArgList}}) {{.ReturnArgTypeList}}
+{{end}}
+	// calls tracks calls to the methods.
+	calls struct {
+{{- range .Methods}}
+		// {{.Name}} holds details about calls to the {{.Name}} method.
+		{{.Name}} []struct {
+			{{- range .Params}}
+			// {{.Name | Exported}} is the {{.Name}} argument value.
+			{{.Name | Exported}} {{.TypeString}}
+			{{- end}}
+		}
+{{- end}}
+	}
+{{- range .Methods}}
+	lock{{.Name}} {{$.Imports | SyncPkgQualifier}}.RWMutex
+{{- end}}
+}
+{{range .Methods}}
+// {{.Name}} calls {{.Name}}Func.
+func (mock *{{$mock.MockName}}) {{.Name}}({{.ArgList}}) {{.ReturnArgTypeList}} {
+{{- if not $.StubImpl}}
+	if mock.{{.Name}}Func == nil {
+		panic("{{$mock.MockName}}.{{.Name}}Func: method is nil but {{$mock.InterfaceName}}.{{.Name}} was just called")
+	}
+{{- end}}
+	callInfo := struct {
+		{{- range .Params}}
+		{{.Name | Exported}} {{.TypeString}}
+		{{- end}}
+	}{
+		{{- range .Params}}
+		{{.Name | Exported}}: {{.Name}},
+		{{- end}}
+	}
+	mock.lock{{.Name}}.Lock()
+	mock.calls.{{.Name}} = append(mock.calls.{{.Name}}, callInfo)
+	mock.lock{{.Name}}.Unlock()
+{{- if .Returns}}
+	{{- if $.StubImpl}}
+	if mock.{{.Name}}Func == nil {
+		var (
+		{{- range .Returns}}
+			{{.Name}} {{.TypeString}}
+		{{- end}}
+		)
+		return {{.ReturnArgNameList}}
+	}
+	{{- end}}
+	return mock.{{.Name}}Func({{.ArgCallList}})
+{{- else}}
+	{{- if $.StubImpl}}
+	if mock.{{.Name}}Func == nil {
+		return
+	}
+	{{- end}}
+	mock.{{.Name}}Func({{.ArgCallList}})
+{{- end}}
+}
+
+// {{.Name}}Calls gets all the calls that were made to {{.Name}}.
+// Check the length with:
+//     len(mocked{{$mock.InterfaceName}}.{{.Name}}Calls())
+func (mock *{{$mock.MockName}}) {{.Name}}Calls() []struct {
+		{{- range .Params}}
+		{{.Name | Exported}} {{.TypeString}}
+		{{- end}}
+	} {
+	var calls []struct {
+		{{- range .Params}}
+		{{.Name | Exported}} {{.TypeString}}
+		{{- end}}
+	}
+	mock.lock{{.Name}}.RLock()
+	calls = mock.calls.{{.Name}}
+	mock.lock{{.Name}}.RUnlock()
+	return calls
+}
+{{end -}}
+{{end -}}`
+
+// This list comes from the golint codebase. Golint will complain about any of
+// these being mixed-case, like "Id" instead of "ID".
+var golintInitialisms = []string{
+	"ACL", "API", "ASCII", "CPU", "CSS", "DNS", "EOF", "GUID", "HTML", "HTTP", "HTTPS", "ID", "IP", "JSON", "LHS",
+	"QPS", "RAM", "RHS", "RPC", "SLA", "SMTP", "SQL", "SSH", "TCP", "TLS", "TTL", "UDP", "UI", "UID", "UUID", "URI",
+	"URL", "UTF8", "VM", "XML", "XMPP", "XSRF", "XSS",
+}
+
+var templateFuncs = template.FuncMap{
+	"ImportStatement": func(imprt *registry.Package) string {
+		if imprt.Alias == "" {
+			return `"` + imprt.Path() + `"`
+		}
+		return imprt.Alias + ` "` + imprt.Path() + `"`
+	},
+	"SyncPkgQualifier": func(imports []*registry.Package) string {
+		for _, imprt := range imports {
+			if imprt.Path() == "sync" {
+				return imprt.Qualifier()
+			}
+		}
+
+		return "sync"
+	},
+	"Exported": func(s string) string {
+		if s == "" {
+			return ""
+		}
+		for _, initialism := range golintInitialisms {
+			if strings.ToUpper(s) == initialism {
+				return initialism
+			}
+		}
+		return strings.ToUpper(s[0:1]) + s[1:]
+	},
+}

internal/template/template_data.go

@@ -0,0 +1,125 @@
+package template
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/matryer/moq/internal/registry"
+)
+
+// Data is the template data used to render the Moq template.
+type Data struct {
+	PkgName         string
+	SrcPkgQualifier string
+	Imports         []*registry.Package
+	Mocks           []MockData
+	StubImpl        bool
+	SkipEnsure      bool
+}
+
+// MocksSomeMethod returns true of any one of the Mocks has at least 1
+// method.
+func (d Data) MocksSomeMethod() bool {
+	for _, m := range d.Mocks {
+		if len(m.Methods) > 0 {
+			return true
+		}
+	}
+
+	return false
+}
+
+// MockData is the data used to generate a mock for some interface.
+type MockData struct {
+	InterfaceName string
+	MockName      string
+	Methods       []MethodData
+}
+
+// MethodData is the data which represents a method on some interface.
+type MethodData struct {
+	Name    string
+	Params  []ParamData
+	Returns []ParamData
+}
+
+// ArgList is the string representation of method parameters, ex:
+// 's string, n int, foo bar.Baz'.
+func (m MethodData) ArgList() string {
+	params := make([]string, len(m.Params))
+	for i, p := range m.Params {
+		params[i] = p.MethodArg()
+	}
+	return strings.Join(params, ", ")
+}
+
+// ArgCallList is the string representation of method call parameters,
+// ex: 's, n, foo'. In case of a last variadic parameter, it will be of
+// the format 's, n, foos...'
+func (m MethodData) ArgCallList() string {
+	params := make([]string, len(m.Params))
+	for i, p := range m.Params {
+		params[i] = p.CallName()
+	}
+	return strings.Join(params, ", ")
+}
+
+// ReturnArgTypeList is the string representation of method return
+// types, ex: 'bar.Baz', '(string, error)'.
+func (m MethodData) ReturnArgTypeList() string {
+	params := make([]string, len(m.Returns))
+	for i, p := range m.Returns {
+		params[i] = p.TypeString()
+	}
+	if len(m.Returns) > 1 {
+		return fmt.Sprintf("(%s)", strings.Join(params, ", "))
+	}
+	return strings.Join(params, ", ")
+}
+
+// ReturnArgNameList is the string representation of values being
+// returned from the method, ex: 'foo', 's, err'.
+func (m MethodData) ReturnArgNameList() string {
+	params := make([]string, len(m.Returns))
+	for i, p := range m.Returns {
+		params[i] = p.Name()
+	}
+	return strings.Join(params, ", ")
+}
+
+// ParamData is the data which represents a parameter to some method of
+// an interface.
+type ParamData struct {
+	Var      *registry.Var
+	Variadic bool
+}
+
+// Name returns the name of the parameter.
+func (p ParamData) Name() string {
+	return p.Var.Name
+}
+
+// MethodArg is the representation of the parameter in the function
+// signature, ex: 'name a.Type'.
+func (p ParamData) MethodArg() string {
+	if p.Variadic {
+		return fmt.Sprintf("%s ...%s", p.Name(), p.TypeString()[2:])
+	}
+	return fmt.Sprintf("%s %s", p.Name(), p.TypeString())
+}
+
+// CallName returns the string representation of the parameter to be
+// used for a method call. For a variadic paramter, it will be of the
+// format 'foos...'.
+func (p ParamData) CallName() string {
+	if p.Variadic {
+		return p.Name() + "..."
+	}
+	return p.Name()
+}
+
+// TypeString returns the string representation of the type of the
+// parameter.
+func (p ParamData) TypeString() string {
+	return p.Var.TypeString()
+}

internal/template/template_test.go

@@ -0,0 +1,55 @@
+package template
+
+import (
+	"go/types"
+	"testing"
+
+	"github.com/matryer/moq/internal/registry"
+)
+
+func TestTemplateFuncs(t *testing.T) {
+	t.Run("Exported", func(t *testing.T) {
+		f := templateFuncs["Exported"].(func(string) string)
+		if f("") != "" {
+			t.Errorf("Exported(...) want: ``; got: `%s`", f(""))
+		}
+		if f("var") != "Var" {
+			t.Errorf("Exported(...) want: `Var`; got: `%s`", f("var"))
+		}
+	})
+
+	t.Run("ImportStatement", func(t *testing.T) {
+		f := templateFuncs["ImportStatement"].(func(*registry.Package) string)
+		pkg := registry.NewPackage(types.NewPackage("xyz", "xyz"))
+		if f(pkg) != `"xyz"` {
+			t.Errorf("ImportStatement(...): want: `\"xyz\"`; got: `%s`", f(pkg))
+		}
+
+		pkg.Alias = "x"
+		if f(pkg) != `x "xyz"` {
+			t.Errorf("ImportStatement(...): want: `x \"xyz\"`; got: `%s`", f(pkg))
+		}
+	})
+
+	t.Run("SyncPkgQualifier", func(t *testing.T) {
+		f := templateFuncs["SyncPkgQualifier"].(func([]*registry.Package) string)
+		if f(nil) != "sync" {
+			t.Errorf("SyncPkgQualifier(...): want: `sync`; got: `%s`", f(nil))
+		}
+		imports := []*registry.Package{
+			registry.NewPackage(types.NewPackage("sync", "sync")),
+			registry.NewPackage(types.NewPackage("github.com/some/module", "module")),
+		}
+		if f(imports) != "sync" {
+			t.Errorf("SyncPkgQualifier(...): want: `sync`; got: `%s`", f(imports))
+		}
+
+		syncPkg := registry.NewPackage(types.NewPackage("sync", "sync"))
+		syncPkg.Alias = "stdsync"
+		otherSyncPkg := registry.NewPackage(types.NewPackage("github.com/someother/sync", "sync"))
+		imports = []*registry.Package{otherSyncPkg, syncPkg}
+		if f(imports) != "stdsync" {
+			t.Errorf("SyncPkgQualifier(...): want: `stdsync`; got: `%s`", f(imports))
+		}
+	})
+}