On 19th July 2019, I attended the #MidsTest meetup in Coventry where I gave my second 99 second talk. This time, I brought a prop – a block from a quilt I’m currently making. This blog post is based on the talk I gave.
One of my hobbies includes sewing. At the moment I’m working on a patchwork quilt which will be a wedding gift for my sister-in-law who is getting married in August.
A patchwork quilt is made up of hundreds of small pieces of fabric, sewn together to create blocks. These are then sewn together to make the completed quilt. The main image for this post is one of several blocks which will be included in the final quilt.
You’re probably wondering where I’m doing with this!
Unit and Integration Testing
Those small pieces of fabric that make up the quilt – rectangles, squares and triangles – have to be unit tested before being used to make the quilt. Any that have not bee cut to the correct shape and size could result in a major bug finding its way to the completed quite.
Once the ‘units’ of fabric have been tested, they are sewn together into smaller blocks. Before sewing the blocks together, they have to be integration tested. Incorrect seam widths or wrong side of the fabric being used are common bugs that can affect the overall design of the quilt.
Saving time by finding defects earlier
These smaller blocks get stitched together to make bigger blocks, which are sewn together to make even bigger blocks. Eventually, all the blocks are sewn together to complete the entire quilt. Each block was integration tested before being used to make a bigger block.
All the testing that takes place early in the quilts development helps reduce the risk of more critical defects being introduced later on. Additionally, bugs found in the smaller blocks are a lot easier to fix than ones found in the bigger ones. The stitches have to be unpicked and the pieces of fabric sewn back together. Defects on smaller blocks are quicker to fix because there are fewer stitches that need unpicking – there are fewer dependencies.
All that testing, why are there still bugs?
Unfortunately, no amount of testing will completely eliminate all bugs. It helps drastically reduce the number of defects that find their way into the final product – but doesn’t eliminate them altogether.
No matter how careful I am, the quilts I make all have minor flaws in them. However, these are minor issues that don’t significantly affect the design. Any major defects that could have affected the quilts design were eliminated early on. If they had been found later, once the quilt was complete, they would be a lot harder to fix.
Why don’t I fix every defect? If I stopped to fix every defect then there is a risk that the quilt won’t get completed in time for my sister-in-laws wedding. In software development, the risks are normally a lot greater than that. Delaying the release costs the business money, sometimes more than if a defect was released to the live environment.
It is not always feasible to fix every single defect – especially if they are minor ones. A little more effort on unit and integration testing can reduce the number of bugs that need to be fixed later.