Enhance documentation for API client and vehicle structures; improve test function naming for clarity

utils_test.go

@@ -7,6 +7,7 @@ import (
 	"time"
 )
 
+// timestamp returns the current time in milliseconds since epoch as a string.
 func TestTimestamp(t *testing.T) {
 	ts1 := timestamp()
 	time.Sleep(1 * time.Millisecond)
@@ -22,6 +23,7 @@ func TestTimestamp(t *testing.T) {
 	}
 }
 
+// timestamp returns the current time in milliseconds since epoch as a string.
 func TestTimestamp_Format(t *testing.T) {
 	ts := timestamp()
 	matched, err := regexp.MatchString(`^\d+$`, ts)
@@ -33,6 +35,7 @@ func TestTimestamp_Format(t *testing.T) {
 	}
 }
 
+// urlToGen replaces "api_gen" in the URL with the specified generation.
 func TestUrlToGen(t *testing.T) {
 	tests := []struct {
 		url, gen, want string
@@ -51,6 +54,7 @@ func TestUrlToGen(t *testing.T) {
 	}
 }
 
+// vinCheck validates the VIN check digit and returns the corrected VIN.
 func TestVinCheck_Valid(t *testing.T) {
 	// Example valid VIN: 1HGCM82633A004352 (check digit is '3')
 	vin := "1HGCM82633A004352"
@@ -63,6 +67,7 @@ func TestVinCheck_Valid(t *testing.T) {
 	}
 }
 
+// TestVinCheck_InvalidCheckDigit tests a VIN with an incorrect check digit.
 func TestVinCheck_InvalidCheckDigit(t *testing.T) {
 	vin := "1HGCM82633A004352"
 	// Change check digit (9th char) to '9'
@@ -77,6 +82,7 @@ func TestVinCheck_InvalidCheckDigit(t *testing.T) {
 	}
 }
 
+// TestVinCheck_WrongLength tests a VIN that is not 17 characters long.
 func TestVinCheck_WrongLength(t *testing.T) {
 	vin := "1234567890123456" // 16 chars
 	valid, corrected := vinCheck(vin)
@@ -88,6 +94,7 @@ func TestVinCheck_WrongLength(t *testing.T) {
 	}
 }
 
+// transcodeDigits computes the sum of the VIN digits according to the VIN rules.
 func TestTranscodeDigits(t *testing.T) {
 	// Use a known VIN and manually compute the sum
 	vin := "1HGCM82633A004352"
@@ -99,6 +106,7 @@ func TestTranscodeDigits(t *testing.T) {
 	}
 }
 
+// TestVinCheck_XCheckDigit tests a VIN with 'X' as the check digit.
 func TestVinCheck_XCheckDigit(t *testing.T) {
 	// VIN with check digit 'X'
 	vin := "1M8GDM9AXKP042788"
@@ -111,6 +119,7 @@ func TestVinCheck_XCheckDigit(t *testing.T) {
 	}
 }
 
+// TestUrlToGen_NoApiGen tests the case where the URL does not contain "api_gen".
 func TestUrlToGen_NoApiGen(t *testing.T) {
 	url := "https://host/endpoint"
 	gen := "g1"