Module 1: Unit Testing (The Safety Inspector)

📚 Module 1: Unit Testing

Course ID: GO-301
Subject: The Safety Inspector

In Go, testing is built right into the language. You don’t need external libraries. A Senior Developer never says “I think it works.” They say “My tests prove it works.”

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🏗️ Step 1: The Test File

A test file always ends in _test.go.

🧩 The Analogy: The Safety Inspector

• You have your factory (The Code).
• The Safety Inspector (The Test File) arrives with a clipboard.
• They try to “Break” your code to see if it handles mistakes correctly.

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🏗️ Step 2: Table-Driven Tests

Professional Go developers use Table-Driven Tests.

🧩 The Analogy: The Checklist

Instead of writing 10 separate tests, you write one Checklist (The Table) with inputs and expected outputs.

• Input: 2 + 2, Expected: 4
• Input: 10 + 0, Expected: 10
• Input: -1 + 5, Expected: 4

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🏗️ Step 3: In Code

func TestAdd(t *testing.T) {
    // 1. The Checklist (Table)
    tests := []struct {
        a, b, expected int
    }{
        {1, 1, 2},
        {10, 20, 30},
        {0, 0, 0},
    }

    // 2. Loop through the checklist
    for _, tt := range tests {
        result := Add(tt.a, tt.b)
        if result != tt.expected {
            t.Errorf("Error! %d + %d expected %d, but got %d", tt.a, tt.b, tt.expected, result)
        }
    }
}

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🥅 Module 1 Review

1. _test.go: The naming rule for test files.
2. testing.T: The object used to report errors.
3. go test: The command to run your inspector.

:::tip Slow Learner Note Testing feels like “extra work” at first. But it actually saves you time because you don’t have to restart your app and click buttons manually 100 times! :::