Running tests in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the testing package.

Go

import [1]

Drag options to blanks, or click blank then click option'

A"fmt"

B"os"

C"testing"

D"net/http"

Attempts:

3 left

💡 Hint

Common Mistakes

Importing 'fmt' instead of 'testing'.

Forgetting to import any package.

The testing package is imported with "testing" to write test functions.

2fill in blank

medium

Complete the code to define a test function for Go testing.

Go

func TestSum([1] *testing.T) { }

Drag options to blanks, or click blank then click option'

At

Btest

CT

Dctx

Attempts:

3 left

💡 Hint

Common Mistakes

Using uppercase 'T' as parameter name.

Using unrelated parameter names like 'ctx'.

The test function receives a pointer to testing.T, commonly named 't'.

3fill in blank

hard

Fix the error in the test function to fail the test when sum is incorrect.

Go

if sum := 2 + 2; sum != 5 {
    [1].Errorf("Expected 5 but got %d", sum)
}

Drag options to blanks, or click blank then click option'

Afmt

Bt

Clog

Dtesting

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'fmt' or 'log' instead of 't' to report errors.

Using 'testing' package name instead of the parameter.

The test function uses the parameter 't' to report errors with Errorf.

4fill in blank

hard

Fill both blanks to run the test with go test and specify the test file.

Go

go [1] -v [2]

Drag options to blanks, or click blank then click option'

Atest

Brun

Cmain.go

Dsum_test.go

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'run' instead of 'test'.

Specifying a non-test file like 'main.go'.

The command 'go test -v sum_test.go' runs tests verbosely in the specified test file.

5fill in blank

hard

Fill all three blanks to write a table-driven test loop over test cases.

Go

tests := []struct {
    name string
    input int
    want  int
}{
    {"test1", 1, 2},
    {"test2", 2, 4},
}

for _, [1] := range tests {
    t.Run([2].name, func(t *testing.T) {
        got := double([3].input)
        if got != [3].want {
            t.Errorf("got %d, want %d", got, [3].want)
        }
    })
}

Drag options to blanks, or click blank then click option'

Atc

Btest

Dt

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently.

Using 't' as loop variable which conflicts with testing.T.

The loop variable is commonly named 'tc' for test case; it is used to access fields in the test run.

Practice

1. What is the correct way to name a test function in Go so that go test can run it?

easy

A. Start the function name with Test

B. Start the function name with test (lowercase t)

C. Name the function RunTest

D. Name the function CheckTest

Solution

1. Step 1: Understand Go test naming rules

   Go requires test functions to start with an uppercase Test to be recognized by go test.

2. Step 2: Check the options

   Only Start the function name with Test starts with Test exactly, others do not follow the naming convention.

3. Final Answer:

   Start the function name with Test -> Option A

4. Quick Check:

   Test functions start with 'Test' [OK]

Hint: Test functions must start with uppercase 'Test' [OK]

Common Mistakes:

• Using lowercase 'test' at start
• Naming test functions without 'Test' prefix
• Using unrelated prefixes like 'Run' or 'Check'

2. Which of the following is the correct syntax to run tests in a Go module from the command line?

easy

A. go execute test

B. go run test

C. go build test

D. go test

Solution

1. Step 1: Recall Go test command

   The command to run tests in Go is go test.

2. Step 2: Compare options

   Only go test matches the correct command. Others are invalid commands.

3. Final Answer:

   go test -> Option D

4. Quick Check:

   Run tests with 'go test' [OK]

Hint: Use 'go test' to run tests, not 'go run' [OK]

Common Mistakes:

• Using 'go run test' instead of 'go test'
• Trying 'go build test' which builds but doesn't test
• Using non-existent commands like 'go execute test'

3. What will be the output when running go test on this test file?

package main

import "testing"

func TestSum(t *testing.T) {
  if 2+2 != 4 {
    t.Error("Sum failed")
  }
}

medium

A. Syntax error: missing main function

B. FAIL
--- FAIL: TestSum

C. PASS
ok main 0.001s

D. No tests to run

Solution

1. Step 1: Analyze the test logic

   The test checks if 2+2 equals 4, which is true, so no error is called.

2. Step 2: Understand test output

   Since the test passes, go test outputs PASS with timing info.

3. Final Answer:

   PASS ok main 0.001s -> Option C

4. Quick Check:

   Test passes, so output shows PASS [OK]

Hint: If test condition is true, output shows PASS [OK]

Common Mistakes:

• Assuming syntax error due to missing main
• Expecting FAIL when condition is true
• Thinking tests won't run without main function

4. Identify the error in this test function that prevents go test from running it:

package main

import "testing"

func testAdd(t *testing.T) {
  if 1+1 != 2 {
    t.Error("Add failed")
  }
}

medium

A. Missing import of 'fmt' package

B. Function name must start with uppercase 'Test'

C. Test function must return a value

D. Test functions cannot have parameters

Solution

1. Step 1: Check test function naming

   The function is named testAdd with lowercase 't', so go test ignores it.

2. Step 2: Verify other requirements

   Test functions must start with uppercase 'Test' and accept *testing.T parameter, which is correct except the name.

3. Final Answer:

   Function name must start with uppercase 'Test' -> Option B

4. Quick Check:

   Test functions need 'Test' prefix [OK]

Hint: Test functions must start with uppercase 'Test' [OK]

Common Mistakes:

• Thinking test functions need to return a value
• Assuming missing 'fmt' import causes test failure
• Believing test functions cannot have parameters

5. You want to run only tests in the file math_test.go inside your module. Which command should you use?

hard

A. go test math_test.go

B. go test -file math_test.go

C. go test -v

D. go test -run math_test.go

Solution

1. Step 1: Understand how to run tests in a specific file

   Go allows specifying test files directly as arguments to go test.

2. Step 2: Check options for correct usage

   Only go test math_test.go runs tests in the specified file. B uses invalid -file flag, C's go test -v runs all tests verbosely, D's -run matches test names.

3. Final Answer:

   go test math_test.go -> Option A

4. Quick Check:

   Specify test file directly to run its tests [OK]

Hint: Run tests in a file by naming it after 'go test' [OK]

Common Mistakes:

• Using invalid flags like -run or -file with filenames
• Confusing verbose flag -v with file selection
• Not specifying the file and running all tests