Add CAT_FASTQ tests for a single non-paired file

The test is written to expect that the input file will be renamed, but the
contents will remain the same, i.e. the test uses the md5 hash of the input
file.

tests/modules/cat/fastq/main.nf

@@ -47,3 +47,12 @@ workflow test_cat_fastq_paired_end_same_name {
 
     CAT_FASTQ ( input )
 }
+
+workflow test_cat_fastq_single_end_single_file {
+    input = [
+        [ id:'test', single_end: true ],
+        [ file(params.test_data['sarscov2']['illumina']['test_1_fastq_gz'], checkIfExists: true) ]
+    ]
+
+    CAT_FASTQ( input )
+}

tests/modules/cat/fastq/test.yml

@@ -37,3 +37,12 @@
       md5sum: 63f817db7a29a03eb538104495556f66
     - path: ./output/cat/test_2.merged.fastq.gz
       md5sum: fe9f266f43a6fc3dcab690a18419a56e
+
+- name: cat fastq single-end-single-file
+  command: nextflow run ./tests/modules/cat/fastq -entry test_cat_fastq_single_end_single_file -c ./tests/config/nextflow.config -c ./tests/modules/cat/fastq/nextflow.config
+  tags:
+    - cat
+    - cat/fastq
+  files:
+    - path: ./output/cat/test.merged.fastq.gz
+      md5sum: e325ef7deb4023447a1f074e285761af