add unit tests and gpl

Makefile

@@ -37,11 +37,10 @@ install: buildlocal
 	install -o $(UID) -g $(GID) -m 444 $(tool).1 $(PREFIX)/man/man1/
 
 clean:
-	rm -rf $(tool) coverage.out testdata t/out
+	rm -rf $(tool) coverage.* testdata t/out
 
 test: clean
-	mkdir -p t/out
+	go test -cover ./... $(ARGS)
-	go test ./... $(ARGS)
 
 testlint: test lint
 
@@ -60,7 +59,8 @@ singletest:
 
 cover-report:
 	go test ./... -cover -coverprofile=coverage.out
-	go tool cover -html=coverage.out
+	go tool cover -html=coverage.out -o coverage.html
+	chromium coverage.html
 
 goupdate:
 	go get -t -u=patch ./...

cmd/config.go

@@ -1,3 +1,20 @@
+/*
+Copyright © 2025 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
 package cmd
 
 import (

cmd/root.go

@@ -1,3 +1,20 @@
+/*
+Copyright © 2025 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
 package cmd
 
 import (

cmd/times.go

@@ -1,3 +1,20 @@
+/*
+Copyright © 2025 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
 package cmd
 
 import (
@@ -12,20 +29,27 @@ import (
 
 type TimestampProccessor struct {
 	Config
+	Reference time.Time
 }
 
-func NewTP(conf *Config) *TimestampProccessor {
+func NewTP(conf *Config, ref ...time.Time) *TimestampProccessor {
+	// we add some pre-defined formats to modnow
 	formats := []string{
 		time.UnixDate, time.RubyDate,
 		time.RFC1123, time.RFC1123Z, time.RFC3339, time.RFC3339Nano,
 		time.RFC822, time.RFC822Z, time.RFC850,
 		"Mon Jan 02 15:04:05 PM MST 2006", // linux date
-		"Mo. 02 Jan. 2006 15:04:05 MST",   // freebsd date (fails, see golang/go/issues/75576)
 	}
 
 	modnow.TimeFormats = append(modnow.TimeFormats, formats...)
 
-	return &TimestampProccessor{Config: *conf}
+	tp := &TimestampProccessor{Config: *conf, Reference: time.Now()}
+
+	if len(ref) == 1 {
+		tp.Reference = ref[0]
+	}
+
+	return tp
 }
 
 func (tp *TimestampProccessor) ProcessTimestamps() error {
@@ -50,10 +74,9 @@ func (tp *TimestampProccessor) SingleTimestamp(timestamp string) error {
 	return nil
 }
 
-// Parse uses 3 different timestamp parser modules to provide the maximum flexibility
+// Parse uses 3 different timestamp parser modules to provide maximum flexibility
 func (tp *TimestampProccessor) Parse(timestamp string) (time.Time, error) {
-	reference := time.Now()
+	ts, err := anytime.Parse(timestamp, tp.Reference)
-	ts, err := anytime.Parse(timestamp, reference)
 	if err == nil {
 		return ts, nil
 	}
@@ -82,16 +105,20 @@ func (tp *TimestampProccessor) Calc(timestampA, timestampB string) error {
 	switch tp.Mode {
 	case ModeDiff:
 		var diff time.Duration
+
+		// avoid negative results
 		if tsA.Unix() > tsB.Unix() {
 			diff = tsA.Sub(tsB)
 		} else {
 			diff = tsB.Sub(tsA)
 		}
+
 		tp.Print(TPduration{TimestampProccessor: *tp, Data: diff})
 
 	case ModeAdd:
 		seconds := (tsB.Hour() * 3600) + (tsB.Minute() * 60) + tsB.Second()
 		sum := tsA.Add(time.Duration(seconds) * time.Second)
+
 		tp.Print(TPdatetime{TimestampProccessor: *tp, Data: sum})
 	}
 

go.mod

@@ -5,6 +5,7 @@ go 1.23.0
 toolchain go1.23.5
 
 require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
 	github.com/ijt/go-anytime v1.9.2 // indirect
 	github.com/ijt/goparsify v0.0.0-20221203142333-3a5276334b8d // indirect
@@ -15,5 +16,8 @@ require (
 	github.com/knadh/koanf/v2 v2.3.0 // indirect
 	github.com/mitchellh/copystructure v1.2.0 // indirect
 	github.com/mitchellh/reflectwalk v1.0.2 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/spf13/pflag v1.0.10 // indirect
+	github.com/stretchr/testify v1.11.1 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,3 +1,5 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/go-viper/mapstructure/v2 v2.4.0 h1:EBsztssimR/CONLSZZ04E8qAkxNYq4Qp9LvH92wZUgs=
 github.com/go-viper/mapstructure/v2 v2.4.0/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
 github.com/ijt/go-anytime v1.9.2 h1:DmYgVwUiFPNR+n6c1T5P070tlGATRZG4aYNJs6XDUfU=
@@ -18,5 +20,12 @@ github.com/mitchellh/copystructure v1.2.0 h1:vpKXTN4ewci03Vljg/q9QvCGUDttBOGBIa1
 github.com/mitchellh/copystructure v1.2.0/go.mod h1:qLl+cE2AmVv+CoeAwDPye/v+N2HKCj9FbZEVFJRxO9s=
 github.com/mitchellh/reflectwalk v1.0.2 h1:G2LzWKi524PWgd3mLHV8Y5k7s6XUvT0Gef6zxSIeXaQ=
 github.com/mitchellh/reflectwalk v1.0.2/go.mod h1:mSTlrgnPZtwu0c4WaC2kGObEpuNDbx0jmZXqmk4esnw=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/spf13/pflag v1.0.10 h1:4EBh2KAYBwaONj6b2Ye1GiHfwjqyROoF4RwYO+vPwFk=
 github.com/spf13/pflag v1.0.10/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

main.go

@@ -1,3 +1,20 @@
+/*
+Copyright © 2025 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
 package main
 
 import (