Add -no-extra-aliases flag (#6)

Add new flag -no-extra-aliases which if set will trigger an error
if an alias is not defined within the alias config.

README.md

@@ -31,6 +31,18 @@ importas -no-unaliased \
   ./...
 ~~~~
 
+### `-no-extra-aliases` option
+
+By default, importas allows aliases which are not specified by `-alias` flags.
+With `-no-extra-aliases` option, importas does not allow any unspecified aliases.
+
+~~~~
+importas -no-extra-aliases \
+  -alias knative.dev/serving/pkg/apis/autoscaling/v1alpha1:autoscalingv1alpha1 \
+  -alias knative.dev/serving/pkg/apis/serving/v1:servingv1 \
+  ./...
+~~~~
+
 ### Use regular expression
 
 You can specify the package path by regular expression, and alias by regular expression replacement syntax like following snippet.

analyzer.go

@@ -81,17 +81,42 @@ func visitImportSpecNode(config *Config, node *ast.ImportSpec, pass *analysis.Pa
 				TextEdits: findEdits(node, pass.TypesInfo.Uses, path, alias, required),
 			}},
 		})
+	} else if !exists && config.DisallowExtraAliases {
+		pass.Report(analysis.Diagnostic{
+			Pos:     node.Pos(),
+			End:     node.End(),
+			Message: fmt.Sprintf("import %q has alias %q which is not part of config", path, alias),
+			SuggestedFixes: []analysis.SuggestedFix{{
+				Message:   "remove alias",
+				TextEdits: findEdits(node, pass.TypesInfo.Uses, path, alias, ""),
+			}},
+		})
 	}
 }
 
 func findEdits(node ast.Node, uses map[*ast.Ident]types.Object, importPath, original, required string) []analysis.TextEdit {
 	// Edit the actual import line.
+	importLine := strconv.Quote(importPath)
+	if required != "" {
+		importLine = required + " " + importLine
+	}
 	result := []analysis.TextEdit{{
 		Pos:     node.Pos(),
 		End:     node.End(),
-		NewText: []byte(required + " " + strconv.Quote(importPath)),
+		NewText: []byte(importLine),
 	}}
 
+	packageReplacement := required
+	if required == "" {
+		packageParts := strings.Split(importPath, "/")
+		if len(packageParts) != 0 {
+			packageReplacement = packageParts[len(packageParts)-1]
+		} else {
+			// fall back to original
+			packageReplacement = original
+		}
+	}
+
 	// Edit all the uses of the alias in the code.
 	for use, pkg := range uses {
 		pkgName, ok := pkg.(*types.PkgName)
@@ -108,7 +133,7 @@ func findEdits(node ast.Node, uses map[*ast.Ident]types.Object, importPath, orig
 		result = append(result, analysis.TextEdit{
 			Pos:     use.Pos(),
 			End:     use.End(),
-			NewText: []byte(required),
+			NewText: []byte(packageReplacement),
 		})
 	}
 

analyzer_test.go

@@ -17,10 +17,11 @@ func TestAnalyzer(t *testing.T) {
 	testdata := analysistest.TestData()
 
 	testCases := []struct {
-		desc              string
-		pkg               string
-		aliases           stringMap
-		disallowUnaliased bool
+		desc                 string
+		pkg                  string
+		aliases              stringMap
+		disallowUnaliased    bool
+		disallowExtraAliases bool
 	}{
 		{
 			desc: "Invalid imports",
@@ -64,6 +65,11 @@ func TestAnalyzer(t *testing.T) {
 			},
 			disallowUnaliased: true,
 		},
+		{
+			desc:                 "disallow extra alias mode",
+			pkg:                  "f",
+			disallowExtraAliases: true,
+		},
 	}
 
 	for _, test := range testCases {
@@ -111,6 +117,11 @@ func TestAnalyzer(t *testing.T) {
 				t.Fatal(err)
 			}
 
+			noExtraAlisesFlg := a.Flags.Lookup("no-extra-aliases")
+			if err := noExtraAlisesFlg.Value.Set(strconv.FormatBool(test.disallowExtraAliases)); err != nil {
+				t.Fatal(err)
+			}
+
 			analysistest.RunWithSuggestedFixes(t, testdata, a, test.pkg)
 		})
 	}

config.go

@@ -7,9 +7,10 @@ import (
 )
 
 type Config struct {
-	RequiredAlias     map[string]string
-	Rules             []*Rule
-	DisallowUnaliased bool
+	RequiredAlias        map[string]string
+	Rules                []*Rule
+	DisallowUnaliased    bool
+	DisallowExtraAliases bool
 }
 
 func (c *Config) CompileRegexp() error {

flags.go

@@ -11,6 +11,7 @@ func flags(config *Config) flag.FlagSet {
 	fs := flag.FlagSet{}
 	fs.Var(stringMap(config.RequiredAlias), "alias", "required import alias in form path:alias")
 	fs.BoolVar(&config.DisallowUnaliased, "no-unaliased", false, "do not allow unaliased imports of aliased packages")
+	fs.BoolVar(&config.DisallowExtraAliases, "no-extra-aliases", false, "do not allow non-required aliases")
 	return fs
 }
 

testdata/src/f/f.go

@@ -0,0 +1,7 @@
+package main
+
+import no_alias_in_config "fmt" // want `import "fmt" has alias "no_alias_in_config" which is not part of config`
+
+func main() {
+	no_alias_in_config.Println("test")
+}

testdata/src/f/f.go.golden

@@ -0,0 +1,7 @@
+package main
+
+import "fmt" // want `import "fmt" has alias "no_alias_in_config" which is not part of config`
+
+func main() {
+	fmt.Println("test")
+}