My current approach to TDD

This is my current approach to TDD.

For new development:

1. I have a rough idea of what I am going to implement. This is optional: If I don’t or I am implementing something too big, I make a simple diagram with diagram.net.
2. I make a class file
3. I hit Ctrl+Shift+T in IntelliJ to quickly create a corresponding test file. I will using the same keyboard pattern to to quickly switch between test and code while doing TDD.
4. I go Ctrl+Shift+T into the class and write the name of method and arguments it may return. The actual return value is set to null.
5. I Ctrl+Shift+T into the test and write the name of method as follows and mention the “WHEN” and “SHOULD” blocks. I don’t know all “WHEN”/“SHOULD” blocks so I’ll write them as time goes.

• “WHEN” blocks define conditions
• “SHOULD” blocks are atomic and assertable.

class MainTestClass{
...
    @Nested
    @DisplayName("upsert method")
    class UpsertMethodTests{

        @Nested
        @DisplayName("WHEN value IS-NOT in DB")
        class ValueNotInDBTest{
            @Test
            @DisplayName("SHOULD insert value")
            void shouldInsertValue(){
                //empty for now
            }
        }

        @Nested
        @DisplayName("WHEN value IS in DB")
        class ValueInDBTest{
            @Test
            @DisplayName("SHOULD replace value")
            void shouldReplaceValue(){
                //empty for now
            }
        }
    }
...
}

6. After any change after this to code or test, I’ll run the wrote test file.
7. I start writing the tests to specify conditions in one “SHOULD” block. Each test is as accurate as possible and any needed behaviour is either asserted or verified.
8. I Ctrl+Shift+T into class and implement code to pass that particular should.
9. The process of writing “WHEN""SHOULD” blocks, writing the test, CTRL+SHIFT+T and coding in class, running the test again is repeated.

For extending existing functionality:

1. I go the the implementation class and understand it.
2. I Ctrl+Shift+T/switch to the test.
3. I add or a new “WHEN” or “SHOULD” or “x method” class
4. And then repeat the cycle again.

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Relevant Further Reading:

• TDD
• Writing Clean and Fast Unit Tests