test: add test files and docs

README.md

@@ -69,6 +69,35 @@ TACCATGAGGTAGTAGGTTGTATAGTT.....................................................
 .........................................................TATACAATCTACTGTCTTTCCT.        1
 ```
 
+## Example
+
+There is a set of test files available in directory `tests/`. If you are in
+the repository root directory, and all dependencies are installed and
+available, you can use the following command to run a test:
+
+```bash
+ascii_alignment_pileup.R \
+  --verbose \
+  --annotations="tests/test_files/test.gff" \
+  --output-directory="$PWD" \
+  "tests/test_files/test.bed" \
+  "tests/test_files/test.bam"
+```
+
+Note that if you build a Docker image from the provided `Dockerfile` or pull
+one of the prebuilt images (see section [Requirements](#requirements)), the
+test files are included in those images. Therefore, you can also run the tests
+in a container. To do that, start a container with:
+
+```bash
+docker run --rm -it <IMAGE_ID> /bin/bash
+```
+
+Then run the test command above.
+
+In both cases, a successful test will create a file
+`test.hsa-let-7a-1.min.1.pileup.tab` in the current working directory.
+
 ## Options
 
 ```console

tests/test_files/test.bed

+9	94175956	94176036	hsa-let-7a-1	0	+

tests/test_files/test.gff

+9	.	miRNA_primary_transcript	94175957	94176036	.	+	.	ID=MI0000060;Alias=MI0000060;Name=hsa-let-7a-1
+9	.	miRNA	94175962	94175983	.	+	.	ID=MIMAT0000062_2;Alias=MIMAT0000062;Name=hsa-let-7a-5p;Derives_from=MI0000060
+9	.	miRNA	94176013	94176033	.	+	.	ID=MIMAT0004481_1;Alias=MIMAT0004481;Name=hsa-let-7a-3p;Derives_from=MI0000060