Add the imports-blacklist rule (#68)

* Add the imports-blacklist rule with tests

* Add the imports-blacklist rule to README.md

* Update the imports-blacklist rule to use map[string]bool so that we can have the algorithm in Visit below with O(n) instead of O(n*m)

* Fix the imports-blacklist rule to be case sensitive

.gitignore

@@ -1,4 +1,4 @@
 golinter
 revive
 vendor
-
+*.swp

README.md

@@ -270,6 +270,7 @@ List of all available rules. The rules ported from `golint` are left unchanged a
 | `bool-literal-in-expr`|  n/a   | Suggests removing Boolean literals from logic expressions        |    no    |  no   |
 | `redefines-builtin-id`|  n/a   | Warns on redefinitions of builtin identifiers                    |    no    |  no   |
 | `function-result-limit` |  int | Specifies the maximum number of results a function can return    |    no    |  no   |
+| `imports-blacklist`   | []string | Disallows importing the specified packages                     |    no    |  no   |
 
 ## Configurable rules
 

config.go

@@ -64,6 +64,7 @@ var allRules = append([]lint.Rule{
 	&rule.ConstantLogicalExprRule{},
 	&rule.BoolLiteralRule{},
 	&rule.RedefinesBuiltinIDRule{},
+	&rule.ImportsBlacklistRule{},
 	&rule.FunctionResultsLimitRule{},
 }, defaultRules...)
 

fixtures/imports-blacklist.go

@@ -0,0 +1,7 @@
+package fixtures
+
+import (
+	"crypto/md5"  //  MATCH /should not use the following blacklisted import: "crypto/md5"/
+	"crypto/sha1" // MATCH /should not use the following blacklisted import: "crypto/sha1"/
+	"strings"
+)

rule/imports-blacklist.go

@@ -0,0 +1,69 @@
+package rule
+
+import (
+	"fmt"
+	"go/ast"
+
+	"github.com/mgechev/revive/lint"
+)
+
+// ImportsBlacklistRule lints given else constructs.
+type ImportsBlacklistRule struct{}
+
+// Apply applies the rule to given file.
+func (r *ImportsBlacklistRule) Apply(file *lint.File, arguments lint.Arguments) []lint.Failure {
+	var failures []lint.Failure
+	blacklist := make(map[string]bool, len(arguments))
+
+	for _, arg := range arguments {
+		argStr, ok := arg.(string)
+		if !ok {
+			panic(fmt.Sprintf("Invalid argument to the imports-blacklist rule. Expecting a string, got %T", arg))
+		}
+		// we add quotes if nt present, because when parsed, the value of the AST node, will be quoted
+		if len(argStr) > 2 && argStr[0] != '"' && argStr[len(argStr)-1] != '"' {
+			argStr = fmt.Sprintf(`"%s"`, argStr)
+		}
+		blacklist[argStr] = true
+	}
+
+	fileAst := file.AST
+	walker := blacklistedImports{
+		file:    file,
+		fileAst: fileAst,
+		onFailure: func(failure lint.Failure) {
+			failures = append(failures, failure)
+		},
+		blacklist: blacklist,
+	}
+
+	ast.Walk(walker, fileAst)
+
+	return failures
+}
+
+// Name returns the rule name.
+func (r *ImportsBlacklistRule) Name() string {
+	return "imports-blacklist"
+}
+
+type blacklistedImports struct {
+	file      *lint.File
+	fileAst   *ast.File
+	onFailure func(lint.Failure)
+	blacklist map[string]bool
+}
+
+func (w blacklistedImports) Visit(n ast.Node) ast.Visitor {
+	for _, is := range w.fileAst.Imports {
+		if is.Path != nil && !w.file.IsTest() && w.blacklist[is.Path.Value] {
+			w.onFailure(lint.Failure{
+				Confidence: 1,
+				Failure:    fmt.Sprintf("should not use the following blacklisted import: %s", is.Path.Value),
+				Node:       is,
+				Category:   "imports",
+			})
+		}
+	}
+	return nil
+}

test/import-blacklist_test.go

@@ -0,0 +1,16 @@
+package test
+
+import (
+	"testing"
+
+	"github.com/mgechev/revive/lint"
+	"github.com/mgechev/revive/rule"
+)
+
+func TestImportsBlacklist(t *testing.T) {
+	args := []interface{}{"crypto/md5", "crypto/sha1"}
+
+	testRule(t, "imports-blacklist", &rule.ImportsBlacklistRule{}, &lint.RuleConfig{
+		Arguments: args,
+	})
+}