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Measuring Coverage with XcodeCoverage, xctool, & Make

23 Mar 2015

The Pieces

XcodeCoverage

The XodeCoverage project is a set of shell scripts bundled with lcov to measure lines of code coverage during execution of instrumented test builds.

In this example, the scripts are used to generate an HTML coverage report (with a few modifications made in my fork to customize report location).

xctool

Facebook created the xctool command-line program to provide an easier way to build and test Xcode projects.

In this example, the tool is used to build and run Objective-C unit tests from the command line.

Make

Make is usually my default entry point for creating builds, running tests, and generating reports. I like putting this sort of automation in a Makefile because, for basic tasks, the syntax is fairly minimal and make is ubiquitous on most platforms.

Putting Them Together

The Makefile

First, we define few shared variables that can be common to all projects:

WORKSPACE_NAME:=<???>
PROJECT_NAME:=<???>
SOURCE_NAME:=<???>
APP_NAME:=<???>

# Common
ROOT_DIR:=.
PROJECT_DIR:=$(ROOT_DIR)/$(SOURCE_NAME)
SOURCE_DIR:=$(PROJECT_DIR)/$(SOURCE_NAME)
SOURCES:=Makefile $(SOURCE_DIR)/*

# Xcode
XCODE_SCHEME?=$(APP_NAME)
XCODE_CONFIGURATION?=Debug

# xctool
XCTOOL:=xctool
XCTOOL_RESULTS_REPORTER?=pretty
XCTOOL_ARGS_SHARED:=-scheme $(XCODE_SCHEME) -configuration \
    $(XCODE_CONFIGURATION) -reporter user-notifications
XCTOOL_ARGS_TEST:=-reporter $(XCTOOL_RESULTS_REPORTER)

# XcodeCoverage
XCODECOVERAGE_DIR:=$(PROJECT_DIR)/XcodeCoverage
XCODECOVERAGE_GETCOV:=$(XCODECOVERAGE_DIR)/getcov
XCODECOVERAGE_CLEANCOV:=$(XCODECOVERAGE_DIR)/cleancov

and a few more variables dictating where we’d like coverage output to go:

COVERAGE_DIR:=$(ROOT_DIR)/coverage
COVERAGE_LOG:=$(COVERAGE_DIR)/getcov.log
COVERAGE_REPORT:=$(COVERAGE_DIR)/index.html

The test target is defined as:

.PHONY: test
test: $(COVERAGE_LOG)
$(COVERAGE_LOG): $(SOURCES)
    $(XCODECOVERAGE_CLEANCOV)
    $(XCTOOL) test $(XCTOOL_ARGS_SHARED) $(XCTOOL_ARGS_TEST)
    mkdir -p $(COVERAGE_DIR) && \
        $(XCODECOVERAGE_GETCOV) $(PROJECT_NAME) $(COVERAGE_DIR) > \
            $(COVERAGE_LOG)
    tail -n 3 $(COVERAGE_LOG)

which will:

  1. Delete the old coverage data
  2. Build and run the unit tests
  3. Parse the generated coverage data
  4. Generate an HTML coverage report
  5. Display the percentage of lines coverage

A shortcut to open the coverage report is defined as:

.PHONY: read-cov
read-cov: $(COVERAGE_INDEX)
    open $(COVERAGE_INDEX)

$(COVERAGE_INDEX): $(COVERAGE_LOG)

Example Output

Running $ make test displays something like:

./MyProject/XcodeCoverage/cleancov
Deleting all .da files in /Users/Browning/Library/Developer/Xcode/DerivedData/MyWorkspace/Build/Intermediates/MyProject.build/Debug-iphonesimulator/MyProject.build/Objects-normal/x86_64 and subdirectories
Done.

xctool test -scheme MyProject -configuration Debug -reporter user-notifications -reporter pretty
[Info] Loading settings for scheme 'MyProject' ... (1950 ms)

=== TEST ===

  xcodebuild build build
    MyProject / MyProject (Debug)
      ✓ Check dependencies (111 ms)
      ✓ Write auxiliary files (0 ms)
      ✓ Compile BatterySensor.m (574 ms)
      ...
      ✓ Compile Platform.m (68 ms)
      0 errored, 0 warning (1315 ms)

  [Info] Collecting info for testables... (1196 ms)
  run-test MyProjectTests.xctest (iphonesimulator8.2, iPad Air, application-test)
    [Info] Installed 'MyProject'. (1392 ms)
    [Info] Launching test host and running tests ... (0 ms)
    ✓ -[BatterySensorCellTestCase testSensorLevel] (5 ms)
    ...
    ✓ -[GroupManagerTestCase testCanCreateGroup] (0 ms)
    99 passed, 0 failed, 0 errored, 99 total (9999 ms)

** TEST SUCCEEDED: 99 passed, 0 failed, 0 errored, 99 total ** (99999 ms)

mkdir -p ./coverage && ./MyProject/XcodeCoverage/getcov MyProject ./coverage > ./coverage/getcov.log

tail -n 3 ./coverage/getcov.log
Overall coverage rate:
  lines......: 17.6% (3676 of 20867 lines)
  functions..: 19.5% (817 of 4192 functions)

Running $ make read-cov launches a report similar to:

sample-lcov-html-report

See a typo? Help me edit this post.

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