Separating lib from cli (#655)

* Separating lib from cli

* Renamed NewRevive to New

* Added GetLintFailures helper function

* Moved formatter to call to format since that's when it's needed

* makes fields of Revive struct non-public

* minor modifs in tests: remove unnamed constats

* Added lint package management to lint command

* README message for using revive as a library

* README formatting

* Removed unused method

* Slightly improved wording in README

* Handling format errors

* Renaming file to better reflect intent

* Refactoring pattern usage

* README heads

* renames excludePaths into excludePatterns

Co-authored-by: Bernardo Heynemann <bernardo.heynemann@coinbase.com>
Co-authored-by: chavacava <salvadorcavadini+github@gmail.com>

revivelib/core_internal_test.go

@@ -0,0 +1,69 @@
+package revivelib
+
+import (
+	"testing"
+
+	"github.com/mgechev/revive/config"
+	"github.com/mgechev/revive/lint"
+)
+
+func TestReviveCreateInstance(t *testing.T) {
+	revive := getMockRevive(t)
+
+	if revive.config == nil {
+		t.Fatal("Could not load config.")
+	}
+
+	if revive.maxOpenFiles != 2048 {
+		t.Fatal("Expected MaxOpenFiles to be 2048")
+	}
+
+	if revive.lintingRules == nil || len(revive.lintingRules) == 0 {
+		t.Fatal("Linting rules not loaded.")
+	}
+
+	rules := map[string]lint.Rule{}
+	for _, rule := range revive.lintingRules {
+		rules[rule.Name()] = rule
+	}
+
+	if _, ok := rules["mock-rule"]; !ok {
+		t.Fatal("Didn't load mock rule.")
+	}
+
+	if revive.config.ErrorCode != 1 && revive.config.WarningCode != 1 {
+		t.Fatal("Didn't set the codes in the config instance.")
+	}
+}
+
+type mockRule struct {
+}
+
+func (r *mockRule) Name() string {
+	return "mock-rule"
+}
+
+func (r *mockRule) Apply(file *lint.File, arguments lint.Arguments) []lint.Failure {
+	return nil
+}
+
+func getMockRevive(t *testing.T) *Revive {
+	t.Helper()
+
+	conf, err := config.GetConfig("../defaults.toml")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	revive, err := New(
+		conf,
+		true,
+		2048,
+		NewExtraRule(&mockRule{}, lint.RuleConfig{}),
+	)
+	if err != nil {
+		t.Fatal(err.Error())
+	}
+
+	return revive
+}