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Use the go test -cover command in Go unit testing to measure coverage and specify the -cover or -coverprofile option to generate the results; the -covermode option sets the coverage mode (set, count, or atomic). Practical cases demonstrate how to write tests and generate coverage reports using coverage configuration files and the go tool cover command.
How to use coverage tool to test coverage in Golang unit testing
Coverage tool is very important in unit testing because it Can help you identify untested parts of your code. This is critical to ensure the quality and reliability of your code. In Golang, you can use the go test -cover
command to measure coverage in unit tests.
Install the coverage tool
To use the coverage tool in Golang, you need to install it. You can install it using the following command:
go install golang.org/x/tools/cmd/cover
Measure coverage
To measure the coverage of unit tests, use the go test
command and Specify the -cover
flag. This flag can then accept the following values:
-covermode=mode: Set the coverage mode. Acceptable values include:
Practical case
The following is a brief example demonstrating how to measure coverage in Golang unit testing:
main.go
package main import ( "fmt" "strconv" ) // Add two numbers func Add(a, b int) int { return a + b } // Convert a string to a number func StrToInt(s string) int { n, err := strconv.Atoi(s) if err != nil { fmt.Println(err.Error()) return 0 } return n }
main_test.go
package main import ( "testing" ) func TestAdd(t *testing.T) { tests := []struct { a int b int want int }{ {1, 2, 3}, {0, 0, 0}, {-1, -1, -2}, } for _, tt := range tests { t.Run(fmt.Sprintf("TestAdd%d_%d", tt.a, tt.b), func(t *testing.T) { if got := Add(tt.a, tt.b); got != tt.want { t.Errorf("Add(%d, %d) = %d, want %d", tt.a, tt.b, got, tt.want) } }) } } func TestStrToInt(t *testing.T) { tests := []struct { s string want int }{ {"1", 1}, {"0", 0}, {"-1", -1}, } for _, tt := range tests { t.Run(fmt.Sprintf("TestStrToInt%s", tt.s), func(t *testing.T) { if got := StrToInt(tt.s); got != tt.want { t.Errorf("StrToInt(%s) = %d, want %d", tt.s, got, tt.want) } }) } } func TestCoverage(t *testing.T) { t.Run("Add", func(t *testing.T) { coverProfile := "add_coverage.out" args := []string{"-test.coverprofile=" + coverProfile, "-test.covermode=set"} cmd := exec.Command("go", "test", args...) if err := cmd.Run(); err != nil { t.Fatalf("Could not run coverage test: %v", err) } }) t.Run("StrToInt", func(t *testing.T) { coverProfile := "str_int_coverage.out" args := []string{"-test.coverprofile=" + coverProfile, "-test.covermode=set"} cmd := exec.Command("go", "test", args...) if err := cmd.Run(); err != nil { t.Fatalf("Could not run coverage test: %v", err) } }) }
Execute the following command at the command line to generate a coverage report:
go test -test.coverprofile=coverage.out
This will create a coverage report in the coverage.out
file. You can view the report using the go tool cover
command:
go tool cover -html=coverage.out
This will open an HTML report in your browser showing the lines of code and files that were not covered.
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