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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"go/ast"
"go/types"
"strings"
"unicode"
"unicode/utf8"
)
func init() {
register("tests",
"check for common mistaken usages of tests/documentation examples",
checkTestFunctions,
funcDecl)
}
func isExampleSuffix(s string) bool {
r, size := utf8.DecodeRuneInString(s)
return size > 0 && unicode.IsLower(r)
}
func isTestSuffix(name string) bool {
if len(name) == 0 {
// "Test" is ok.
return true
}
r, _ := utf8.DecodeRuneInString(name)
return !unicode.IsLower(r)
}
func isTestParam(typ ast.Expr, wantType string) bool {
ptr, ok := typ.(*ast.StarExpr)
if !ok {
// Not a pointer.
return false
}
// No easy way of making sure it's a *testing.T or *testing.B:
// ensure the name of the type matches.
if name, ok := ptr.X.(*ast.Ident); ok {
return name.Name == wantType
}
if sel, ok := ptr.X.(*ast.SelectorExpr); ok {
return sel.Sel.Name == wantType
}
return false
}
func lookup(name string, scopes []*types.Scope) types.Object {
for _, scope := range scopes {
if o := scope.Lookup(name); o != nil {
return o
}
}
return nil
}
func extendedScope(f *File) []*types.Scope {
scopes := []*types.Scope{f.pkg.typesPkg.Scope()}
if f.basePkg != nil {
scopes = append(scopes, f.basePkg.typesPkg.Scope())
} else {
// If basePkg is not specified (e.g. when checking a single file) try to
// find it among imports.
pkgName := f.pkg.typesPkg.Name()
if strings.HasSuffix(pkgName, "_test") {
basePkgName := strings.TrimSuffix(pkgName, "_test")
for _, p := range f.pkg.typesPkg.Imports() {
if p.Name() == basePkgName {
scopes = append(scopes, p.Scope())
break
}
}
}
}
return scopes
}
func checkExample(fn *ast.FuncDecl, f *File, report reporter) {
fnName := fn.Name.Name
if params := fn.Type.Params; len(params.List) != 0 {
report("%s should be niladic", fnName)
}
if results := fn.Type.Results; results != nil && len(results.List) != 0 {
report("%s should return nothing", fnName)
}
if filesRun && !includesNonTest {
// The coherence checks between a test and the package it tests
// will report false positives if no non-test files have
// been provided.
return
}
if fnName == "Example" {
// Nothing more to do.
return
}
var (
exName = strings.TrimPrefix(fnName, "Example")
elems = strings.SplitN(exName, "_", 3)
ident = elems[0]
obj = lookup(ident, extendedScope(f))
)
if ident != "" && obj == nil {
// Check ExampleFoo and ExampleBadFoo.
report("%s refers to unknown identifier: %s", fnName, ident)
// Abort since obj is absent and no subsequent checks can be performed.
return
}
if len(elems) < 2 {
// Nothing more to do.
return
}
if ident == "" {
// Check Example_suffix and Example_BadSuffix.
if residual := strings.TrimPrefix(exName, "_"); !isExampleSuffix(residual) {
report("%s has malformed example suffix: %s", fnName, residual)
}
return
}
mmbr := elems[1]
if !isExampleSuffix(mmbr) {
// Check ExampleFoo_Method and ExampleFoo_BadMethod.
if obj, _, _ := types.LookupFieldOrMethod(obj.Type(), true, obj.Pkg(), mmbr); obj == nil {
report("%s refers to unknown field or method: %s.%s", fnName, ident, mmbr)
}
}
if len(elems) == 3 && !isExampleSuffix(elems[2]) {
// Check ExampleFoo_Method_suffix and ExampleFoo_Method_Badsuffix.
report("%s has malformed example suffix: %s", fnName, elems[2])
}
}
func checkTest(fn *ast.FuncDecl, prefix string, report reporter) {
// Want functions with 0 results and 1 parameter.
if fn.Type.Results != nil && len(fn.Type.Results.List) > 0 ||
fn.Type.Params == nil ||
len(fn.Type.Params.List) != 1 ||
len(fn.Type.Params.List[0].Names) > 1 {
return
}
// The param must look like a *testing.T or *testing.B.
if !isTestParam(fn.Type.Params.List[0].Type, prefix[:1]) {
return
}
if !isTestSuffix(fn.Name.Name[len(prefix):]) {
report("%s has malformed name: first letter after '%s' must not be lowercase", fn.Name.Name, prefix)
}
}
type reporter func(format string, args ...interface{})
// checkTestFunctions walks Test, Benchmark and Example functions checking
// malformed names, wrong signatures and examples documenting nonexistent
// identifiers.
func checkTestFunctions(f *File, node ast.Node) {
if !strings.HasSuffix(f.name, "_test.go") {
return
}
fn, ok := node.(*ast.FuncDecl)
if !ok || fn.Recv != nil {
// Ignore non-functions or functions with receivers.
return
}
report := func(format string, args ...interface{}) { f.Badf(node.Pos(), format, args...) }
switch {
case strings.HasPrefix(fn.Name.Name, "Example"):
checkExample(fn, f, report)
case strings.HasPrefix(fn.Name.Name, "Test"):
checkTest(fn, "Test", report)
case strings.HasPrefix(fn.Name.Name, "Benchmark"):
checkTest(fn, "Benchmark", report)
}
}
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