From ef24c9f594cb348193f56c9935179c273b651f97 Mon Sep 17 00:00:00 2001
From: Dmitrii Malinovskii <you@example.com>
Date: Wed, 19 Jun 2024 21:21:17 +0400
Subject: [PATCH] get language from file name

---
 internal/app/app.feature                      | 83 +++++++++++--------
 internal/app/app.go                           |  9 ++
 internal/app/app_test.go                      | 42 ++++++++++
 internal/app/{languages.go => language.go}    | 14 ++++
 internal/app/testdata/english.feature         |  7 ++
 .../app/testdata/english.sample.en.feature    |  7 ++
 internal/app/testdata/pirate.feature          |  8 ++
 .../testdata/pirate.sample.en-pirate.feature  |  8 ++
 8 files changed, 145 insertions(+), 33 deletions(-)
 rename internal/app/{languages.go => language.go} (82%)
 create mode 100644 internal/app/testdata/english.feature
 create mode 100644 internal/app/testdata/english.sample.en.feature
 create mode 100644 internal/app/testdata/pirate.feature
 create mode 100644 internal/app/testdata/pirate.sample.en-pirate.feature

diff --git a/internal/app/app.feature b/internal/app/app.feature
index edd0e64..94fc97f 100644
--- a/internal/app/app.feature
+++ b/internal/app/app.feature
@@ -1,55 +1,56 @@
 Feature: Application command line tool
+
   Scenario Outline: User wants to generate the output in given format
     When <format> is given
     And  <feature> is provided
     Then the output should be generated
     Examples:
-    | <feature>        | <format> | <assertion> |
-    | app.feature      | go       | does        |
-    | app.feature      | json     | does        |
-    | app.feature      | raw      | does        |
-    | app.feature      | invalid  | does not    |
-    | notfound.feature | raw      | does not    |
+      | <feature>        | <format> | <assertion> |
+      | app.feature      | go       | does        |
+      | app.feature      | json     | does        |
+      | app.feature      | raw      | does        |
+      | app.feature      | invalid  | does not    |
+      | notfound.feature | raw      | does not    |
 
   Scenario Outline: User wants to see usage information
     When <flag> is provided
     Then usage should be printed
     Examples:
-    | <flag> |
-    | --help |
+      | <flag> |
+      | --help |
 
   Scenario Outline: User wants to list built-in templates
     When <flag> is provided
     Then templates should be printed
     Examples:
-    | <flag> |
-    | --list |
+      | <flag> |
+      | --list |
 
   Scenario Outline: User wants to use custom template
     When <template> is provided
     And  <feature> is provided
     Then the output should be generated
     Examples:
-    | <feature>   | <template>                      |
-    | app.feature | ../assets/std.simple.v1.go.tmpl |
-    | app.feature | @/std.simple.v1.go.tmpl         |
-  
+      | <feature>   | <template>                      |
+      | app.feature | ../assets/std.simple.v1.go.tmpl |
+      | app.feature | @/std.simple.v1.go.tmpl         |
+
   Scenario Outline: User wants to set custom package
     When <package> is provided
     Then the output should contain <package>
     Examples:
-    | <package>     |
-    | app_test      |
-    | example_test  |
-  
+      | <package>    |
+      | app_test     |
+      | example_test |
+
   Scenario Outline: User wants to generate a permanent json output
     When -format is json
     And -permanent-ids is <TheSameIDs>
     Then calling generation twice will produce the same output <TheSameIDs>
     Examples:
-    | <TheSameIDs> |
-    | true         |
-    | false        |
+      | <TheSameIDs> |
+      | true         |
+      | false        |
 
   Scenario: User provides an invalid flag
     When flag -invalid is provided
@@ -59,17 +60,17 @@ Feature: Application command line tool
     When <flag> is provided
     Then version is printed
     Examples:
-    | <flag>    |
-    | --version |
-    | -version  |
+      | <flag>    |
+      | --version |
+      | -version  |
 
   Scenario Outline: User specifies a file, but the file is not found
     When inexistent <template> is provided
     And  <feature> is provided
     Then the user receives an error
     Examples:
-    | <feature>   | <template> |
-    | app.feature | not_found  |
+      | <feature>   | <template> |
+      | app.feature | not_found  |
 
   Scenario: User wants to run tests in parallel
     When `scenario.feature` is given
@@ -85,19 +86,35 @@ Feature: Application command line tool
     And the <feature> is provided
     Then the output should be generated
     Examples:
-    | <language>  | <feature>                                      | assertion |
-    | en          | ../generator/examples/simple.feature           | does      |
-    | en-pirate   | ../generator/examples/simple.en-pirate.feature | does      |
-    | unsupported | app.feature                                    | does not  |
+      | <language>  | <feature>                                      | assertion |
+      | en          | ../generator/examples/simple.feature           | does      |
+      | en-pirate   | ../generator/examples/simple.en-pirate.feature | does      |
+      | unsupported | app.feature                                    | does not  |
 
   Scenario Outline: User wants to see all supported natural languages
     When the <flag> is provided
     Then the list of supported natural languages should be printed
     Examples:
-    | <flag>      |
-    | -languages  |
-    | --languages |
+      | <flag>      |
+      | -languages  |
+      | --languages |
 
   Scenario: User wants to see consistent supported natural languages output
     When the user lists supported natural languages several times
     Then the output is the same
+
+  Scenario Outline: User wants to be able to specify the natural language of a feature in its file name
+    When the <language> is specified by the flag
+    And the <feature> is given
+    Then the output should be generated
+    Examples:
+      | <language> | <feature>                                  | assertion |
+      | en-pirate  | ./testdata/pirate.feature                  | does      |
+      |            | ./testdata/pirate.feature                  | does not  |
+      |            | ./testdata/pirate.sample.en-pirate.feature | does      |
+      | wrong      | ./testdata/pirate.sample.en-pirate.feature | does not  |
+      | en         | ./testdata/english.feature                 | does      |
+      |            | ./testdata/english.feature                 | does      |
+      |            | ./testdata/english.sample.en.feature       | does      |
+      | wrong      | ./testdata/english.sample.en.feature       | does not  |
+      |            | app.feature                                | does      |
diff --git a/internal/app/app.go b/internal/app/app.go
index f24fb6e..6161926 100644
--- a/internal/app/app.go
+++ b/internal/app/app.go
@@ -4,6 +4,7 @@ import (
 	"flag"
 	"io"
 	"math/rand"
+	"slices"
 	"strings"
 	"time"
 
@@ -22,6 +23,8 @@ const (
 )
 
 // Run the application.
+//
+//nolint:cyclop // Looks fine to me.
 func Run(arguments []string, out io.Writer, version string) (err error) {
 	flagSet := flag.NewFlagSet(flag.CommandLine.Name(), flag.ContinueOnError)
 	flagSet.SetOutput(out)
@@ -98,6 +101,12 @@ func Run(arguments []string, out io.Writer, version string) (err error) {
 		inputFile = flagSet.Args()[0]
 	}
 
+	if !slices.Contains(arguments, "-language") {
+		if hint := tryFromFileName(inputFile); hint != "" {
+			*language = hint
+		}
+	}
+
 	switch {
 	case *versionCmd:
 		return runVersion(out, version)
diff --git a/internal/app/app_test.go b/internal/app/app_test.go
index 29e3b30..bf531d2 100644
--- a/internal/app/app_test.go
+++ b/internal/app/app_test.go
@@ -1,3 +1,4 @@
+//nolint:goconst // These are auto generated tests.
 package app_test
 
 import (
@@ -201,6 +202,47 @@ func TestApplicationCommandLineTool(t *testing.T) {
 		// Then the output is the same.
 		assert.Equal(t, out1, out2)
 	})
+
+	t.Run("User wants to be able to specify the natural language of a feature in its file name", func(t *testing.T) {
+		t.Parallel()
+
+		type testCase struct {
+			Language  string `field:"<language>"`
+			Feature   string `field:"<feature>"`
+			Assertion string `field:"assertion"`
+		}
+
+		testCases := map[string]testCase{
+			"en-pirate_./testdata/pirate.feature_does":                  {"en-pirate", "./testdata/pirate.feature", "does"},
+			"_./testdata/pirate.feature_does_not":                       {"", "./testdata/pirate.feature", "does not"},
+			"_./testdata/pirate.sample.en-pirate.feature_does":          {"", "./testdata/pirate.sample.en-pirate.feature", "does"},
+			"wrong_./testdata/pirate.sample.en-pirate.feature_does_not": {"wrong", "./testdata/pirate.sample.en-pirate.feature", "does not"},
+			"en_./testdata/english.feature_does":                        {"en", "./testdata/english.feature", "does"},
+			"_./testdata/english.feature_does":                          {"", "./testdata/english.feature", "does"},
+			"_./testdata/english.sample.en.feature_does":                {"", "./testdata/english.sample.en.feature", "does"},
+			"wrong_./testdata/english.sample.en.feature_does_not":       {"wrong", "./testdata/english.sample.en.feature", "does not"},
+			"_app.feature_does":                                         {"", "app.feature", "does"},
+		}
+
+		for name, testCase := range testCases {
+			t.Run(name, func(t *testing.T) {
+				t.Parallel()
+
+				var arguments []string
+
+				// When the <language> is specified by the flag.
+				if testCase.Language != "" {
+					arguments = append(arguments, "-language", testCase.Language)
+				}
+
+				// And the <feature> is given.
+				arguments = append(arguments, testCase.Feature)
+
+				// Then the output should be generated.
+				runApp(t, arguments, testCase.Assertion == "does")
+			})
+		}
+	})
 }
 
 func TestApplicationCommandLineToolCustom(t *testing.T) {
diff --git a/internal/app/languages.go b/internal/app/language.go
similarity index 82%
rename from internal/app/languages.go
rename to internal/app/language.go
index e45caef..2c49a96 100644
--- a/internal/app/languages.go
+++ b/internal/app/language.go
@@ -51,3 +51,17 @@ func featureLanguages() ([]*gherkin.Dialect, error) {
 
 	return dialects, nil
 }
+
+func tryFromFileName(fileName string) string {
+	i := strings.LastIndexAny(fileName, "/\\")
+
+	lastPart := fileName[i+1:]
+
+	parts := strings.Split(lastPart, ".")
+
+	if len(parts) <= 2 {
+		return ""
+	}
+
+	return parts[len(parts)-2]
+}
diff --git a/internal/app/testdata/english.feature b/internal/app/testdata/english.feature
new file mode 100644
index 0000000..7dc2b3f
--- /dev/null
+++ b/internal/app/testdata/english.feature
@@ -0,0 +1,7 @@
+Feature: Guess the word
+
+  The word guess game is a turn-based game for two players.
+  The Maker makes a word for the Breaker to guess. The game
+  is over when the Breaker guesses the Maker's word.
+
+  Example: Maker starts a game
diff --git a/internal/app/testdata/english.sample.en.feature b/internal/app/testdata/english.sample.en.feature
new file mode 100644
index 0000000..7dc2b3f
--- /dev/null
+++ b/internal/app/testdata/english.sample.en.feature
@@ -0,0 +1,7 @@
+Feature: Guess the word
+
+  The word guess game is a turn-based game for two players.
+  The Maker makes a word for the Breaker to guess. The game
+  is over when the Breaker guesses the Maker's word.
+
+  Example: Maker starts a game
diff --git a/internal/app/testdata/pirate.feature b/internal/app/testdata/pirate.feature
new file mode 100644
index 0000000..909eb9a
--- /dev/null
+++ b/internal/app/testdata/pirate.feature
@@ -0,0 +1,8 @@
+Ahoy matey!: Guessin' the Word!
+
+  This be a game o' guessin' words, turn-based and for two scallywags only!
+  The Maker, a cunning buccaneer, chooses a secret word for the Breaker to decipher.
+  The Breaker, a sharp wit, tries to guess the Maker's hidden word.
+  The game be done when the Breaker shouts out the right word!
+
+  Heave to: The Maker starts a game!
diff --git a/internal/app/testdata/pirate.sample.en-pirate.feature b/internal/app/testdata/pirate.sample.en-pirate.feature
new file mode 100644
index 0000000..909eb9a
--- /dev/null
+++ b/internal/app/testdata/pirate.sample.en-pirate.feature
@@ -0,0 +1,8 @@
+Ahoy matey!: Guessin' the Word!
+
+  This be a game o' guessin' words, turn-based and for two scallywags only!
+  The Maker, a cunning buccaneer, chooses a secret word for the Breaker to decipher.
+  The Breaker, a sharp wit, tries to guess the Maker's hidden word.
+  The game be done when the Breaker shouts out the right word!
+
+  Heave to: The Maker starts a game!