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Merge pull request #2101 from WalterBright/unittest-spec
revamp unittest description
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‎spec/unittest.dd

Lines changed: 85 additions & 65 deletions
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@@ -8,87 +8,113 @@ $(GRAMMAR
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$(GNAME UnitTest):
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$(D unittest) $(GLINK2 statement, BlockStatement)
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)
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$(P Unit tests are a builtin framework of test cases
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applied to a module to determine if it is working properly.
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A D program can be run with unit tests enabled or disabled.
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)
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$(P Unit tests are a series of test cases applied to a module to determine
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if it is working properly. Ideally, unit tests should be run every
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time a program is compiled.
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)
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$(P Unit tests are a special function defined like:)
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$(P Unit tests are a special function defined like:)
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---
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unittest
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{
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...test code...
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}
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---
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------
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unittest
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{
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...test code...
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}
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------
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$(P Individual tests are specified in the unit test using $(DDSUBLINK spec/expression, AssertExpression)s.
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Unlike $(I AssertExpression)s used elsewhere, the assert is not assumed to hold, and upon assert
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failure the program is still in a defined state.
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)
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$(P There can be any number of unit test functions in a module,
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including within struct, union and class declarations.
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They are executed in lexical order.
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The order in which the modules are called to run their unit tests is
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implementation defined.
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Stylistically, a unit test for a function should appear immediately
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following it.
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)
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$(P A compiler switch, such as $(DDSUBLINK dmd, switch-unittest, $(B -unittest))
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for $(B dmd), will
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cause the unittest test code to be compiled and incorporated into
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the resulting executable. The unittest code gets run after
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static initialization is run and before the $(D main())
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function is called.
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$(P Unit tests, when enabled, are run after all static initialization is
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complete and before the $(D main()) function is called.
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)
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$(P $(GLINK UnitTest)s must be grammatically correct even if $(B -unittest) is not
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used.)
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$(P For example, given a class $(D Sum) that is used to add two values, a unit
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test can be given:)
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------
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class Sum
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{
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int add(int x, int y) { return x + y; }
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unittest
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---
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class Sum
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{
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Sum sum = new Sum;
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assert(sum.add(3,4) == 7);
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assert(sum.add(-2,0) == -2);
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int add(int x, int y) { return x + y; }
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unittest
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{
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Sum sum = new Sum;
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assert(sum.add(3,4) == 7);
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assert(sum.add(-2,0) == -2);
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}
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}
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}
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------
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---
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$(P When unit tests are enabled, the $(DDSUBLINK spec/version, PredefinedVersions, version identifier)
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$(D unittest) is predefined.
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)
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$(H2 $(LNAME2 attributes_unittest, Attributed Unittests))
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$(P A unittest may be attributed with any of the global function attributes.
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Such unittests are useful in verifying the given attribute(s) on a template
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function:)
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$(P A unittest may be attributed with any of the global function attributes.
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Such unittests are useful in verifying the given attribute(s) on a template
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function:)
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------
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void myFunc(T)(T[] data)
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{
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if (data.length > 2)
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data[0] = data[1];
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}
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---
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void myFunc(T)(T[] data)
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{
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if (data.length > 2)
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data[0] = data[1];
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}
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@safe nothrow unittest
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{
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auto arr = [1,2,3];
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myFunc(arr);
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assert(arr == [2,2,3]);
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}
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------
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@safe nothrow unittest
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{
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auto arr = [1,2,3];
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myFunc(arr);
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assert(arr == [2,2,3]);
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}
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---
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$(P This unittest verifies that $(D myFunc) contains only $(D @safe),
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`nothrow` code. Although this can also be accomplished by attaching these
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attributes to $(D myFunc) itself, that would prevent $(D myFunc) from being
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instantiated with types $(D T) that have $(D @system) or throwing code in their
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$(D opAssign) method, or other methods that $(D myFunc) may call. The above
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idiom allows $(D myFunc) to be instantiated with such types, yet at the same
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time verify that the $(D @system) and throwing behavior is not introduced by
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the code within $(D myFunc) itself.)
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$(IMPLEMENTATION_DEFINED
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$(OL
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$(LI If unit tests are not enabled, the implementation is not required to
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check the $(GLINK UnitTest) for syntactic or semantic correctness.
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This is to reduce the compile time impact of larger unit test sections.
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The tokens must still be valid, and the implementation can merely count
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$(D {) and $(D }) tokens to find the end of the $(GLINK UnitTest)'s $(GLINK2 statement, BlockStatement).
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)
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$(LI The presentation of unit test results to the user.)
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$(LI The method used to enable or disable the unit tests. Use of a compiler
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switch such as $(DDSUBLINK dmd, switch-unittest, $(B -unittest)) to enable
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them is suggested.)
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$(LI The order in which modules are called to run their unit tests.)
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$(LI Whether the program stops on the first unit test failure, or continues running the unit tests.)
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)
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)
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$(BEST_PRACTICE
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$(OL
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$(LI Using unit tests in conjuction with coverage testing
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(such as $(DDSUBLINK dmd, switch-cov, $(B -cov)))
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is effective.)
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$(LI A unit test for a function should appear immediately
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following it.)
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)
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)
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$(P This unittest verifies that $(D myFunc) contains only $(D @safe),
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`nothrow` code. Although this can also be accomplished by attaching these
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attributes to $(D myFunc) itself, that would prevent $(D myFunc) from being
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instantiated with types $(D T) that have $(D @system) or throwing code in their
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$(D opAssign) method, or other methods that $(D myFunc) may call. The above
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idiom allows $(D myFunc) to be instantiated with such types, yet at the same
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time verify that the $(D @system) and throwing behaviour is not introduced by
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the code within $(D myFunc) itself.)
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$(H2 $(LNAME2 documented-unittests, Documented Unittests))
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@@ -197,12 +223,6 @@ code sample generated, even if it is empty or only includes comments
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</dl>
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)
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$(H2 $(LNAME2 versioning, Versioning))
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$(P The $(DDSUBLINK spec/version, PredefinedVersions, version identifier)
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$(D unittest) is predefined if the compilation
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is done with unit tests enabled.
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)
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$(SPEC_SUBNAV_PREV_NEXT errors, Error Handling, garbage, Garbage Collection)
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)

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