add separator checking and return error

service_a/assets/test_8.csv

@@ -0,0 +1,2 @@
+Fecha,Ciudad,Temperatura Máxima (C),Temperatura Mínima (C),Precipitación (mm),Nubosidad (%)
+2025/10/12,Madrid,11,55,6,25,0,10

service_a/internal/domains/meteo/file.go

@@ -47,6 +47,10 @@ func (c *CSV) Parse(r io.Reader) ([]MeteoData, []RejectedMeteoData, error) {
 		return nil, nil, fmt.Errorf("%w: %v", ErrReadingCSVHeader, err)
 	}
 
+	if len(header) == 1 {
+		return nil, nil, fmt.Errorf("%w: invalid separator detected, expected semicolon (;)", ErrCannotParseFile)
+	}
+
 	var meteoDataList []MeteoData
 	var rejectedDataList []RejectedMeteoData
 

service_a/internal/domains/meteo/file_test.go

@@ -15,6 +15,7 @@ func Test_CSV_ParseFile(t *testing.T) {
 		filePath         string
 		expectedInserted int
 		expectedRejected int
+		expectError      bool
 		validateInserted func(t *testing.T, inserted []meteo.MeteoData)
 		validateRejected func(t *testing.T, rejected []meteo.RejectedMeteoData)
 	}{
@@ -109,6 +110,7 @@ func Test_CSV_ParseFile(t *testing.T) {
 			filePath:         "./../../../assets/test_7.csv",
 			expectedInserted: 0,
 			expectedRejected: 1,
+			expectError:      false,
 			validateInserted: func(t *testing.T, inserted []meteo.MeteoData) {
 				assert.Empty(t, inserted)
 			},
@@ -118,6 +120,15 @@ func Test_CSV_ParseFile(t *testing.T) {
 				assert.Equal(t, ";Madrid;11,55;6,25;0;10", rejected[0].RowValue)
 			},
 		},
+		{
+			name:             "invalid separator comma instead of semicolon",
+			filePath:         "./../../../assets/test_8.csv",
+			expectedInserted: 0,
+			expectedRejected: 0,
+			expectError:      true,
+			validateInserted: nil,
+			validateRejected: nil,
+		},
 	}
 
 	for _, tt := range tests {
@@ -127,12 +138,15 @@ func Test_CSV_ParseFile(t *testing.T) {
 			defer file.Close()
 
 			csvIngest := &meteo.CSV{}
-			fileStats := &meteo.FileStats{}
 			inserted, rejected, err := csvIngest.Parse(file)
 
+			if tt.expectError {
+				assert.Error(t, err)
+				assert.ErrorIs(t, err, meteo.ErrCannotParseFile)
+				return
+			}
+
 			assert.NoError(t, err)
-			assert.Equal(t, tt.expectedInserted, fileStats.RowsInserted)
-			assert.Equal(t, tt.expectedRejected, fileStats.RowsRejected)
 
 			if tt.validateInserted != nil {
 				tt.validateInserted(t, inserted)