source_cell: replace #define private public with named friend grants in four tests (#7949)

`magnetism_test`, `atom_pseudo_test`, `pseudo_nc_test` and `read_pp_test` each
switched off access control for their whole translation unit in order to call a
handful of private *methods* -- the format readers and helpers the tests exist
to exercise. No private data member is involved, and none of these files touches
PARAM, so the macro had exactly one cause.

Replace it with an explicit `friend class <fixture>;` on the class under test,
following the existing precedent in source_pw/module_pwdft/dftu_base.h
(`friend class DFTUTest;`) and parameter.h (`friend class TestParameters;`).
This is the fix AGENTS.md rule 10 names, and it narrows a whole-TU override --
which also reinterprets access control inside every standard library header the
TU pulls in -- down to one named, reviewable grant per fixture.

Friendship is not inherited, and a TEST_F body lives in a class derived from the
fixture, so each fixture gains thin forwarding wrappers and the TEST_F bodies
call those. dftu_lcao_test.cpp already documents and uses this arrangement.

- Magnetism: friend MagnetismTest, 1 wrapper (judge_parallel), 2 call sites.
- Pseudopot_upf: friend AtomPseudoTest / NCPPTest / ReadPPTest; 1 + 3 + 8
  wrappers for read_pseudo_upf{,201,_vwr,_blps}, set_pseudo_type, setqfnew,
  trim, trimend, complete_default_{h,atom}; 36 call sites in total.

Public members and public methods the tests already used -- Pseudopot_upf's
complete_default, init_pseudo_reader, average_p, set_upf_q, set_empty_element,
print_pseudo_upf and its public data, and Magnetism's tot_mag/abs_mag/start_mag
-- are untouched and still accessed directly.

No test expectation changed: every wrapper forwards its arguments unmodified and
returns what the private method returns. Macro occurrences in these four files
go 4 -> 0; no `#undef private` is introduced anywhere, and no file whose macro
survives is touched.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: Critsium-xy

source/source_cell/magnetism.h

@@ -5,11 +5,16 @@
 #include "source_base/vector3.h"
 #include <vector>
 
+class MagnetismTest;
+
 /**
  * @brief Class for magnetism calculations.
  */
 class Magnetism
 {
+    /// @brief the unit test drives the private judge_parallel() helper directly
+    friend class MagnetismTest;
+
 public:
     /// @brief Constructor
     Magnetism();

source/source_cell/read_pp.h

@@ -11,6 +11,10 @@
 #include "source_base/matrix.h"
 #include "source_base/realarray.h"
 
+class AtomPseudoTest;
+class NCPPTest;
+class ReadPPTest;
+
 /**
  * @brief Pseudopot_upf class for reading pseudopotential files.
  *
@@ -19,6 +23,12 @@
  */
 class Pseudopot_upf
 {
+    /// @brief the unit tests drive the private format readers and the
+    /// complete_default_* helpers directly; see source_cell/test/
+    friend class AtomPseudoTest;
+    friend class NCPPTest;
+    friend class ReadPPTest;
+
 public:
     /// PP_INFO
     /// PP_HEADER

source/source_cell/test/atom_pseudo_test.cpp

@@ -22,16 +22,22 @@
  *     - bcast upf201 pp info to other processes
  */
 
-#define private public
 #include "source_cell/read_pp.h"
 #include "source_cell/pseudo.h"
 #include "source_cell/atom_pseudo.h"
-#undef private
 class AtomPseudoTest : public testing::Test
 {
 protected:
     std::unique_ptr<Pseudopot_upf> upf{new Pseudopot_upf};
     std::unique_ptr<Atom_pseudo> atom_pseudo{new Atom_pseudo};
+
+    // Pseudopot_upf declares this fixture a friend, but a TEST_F body lives in
+    // a class derived from it, and friendship is not inherited -- so the call
+    // into the private format reader has to happen here.
+    int read_pseudo_upf201(std::ifstream& ifs, Atom_pseudo& pp) const
+    {
+        return upf->read_pseudo_upf201(ifs, pp);
+    }
 };
 
 TEST_F(AtomPseudoTest, SetDSo)
@@ -43,7 +49,7 @@ TEST_F(AtomPseudoTest, SetDSo)
     std::ifstream ifs;
     ifs.open("./support/C.upf");
     const double pseudo_rcut = 15.0;
-    upf->read_pseudo_upf201(ifs, *atom_pseudo);
+    read_pseudo_upf201(ifs, *atom_pseudo);
     upf->complete_default(*atom_pseudo, pseudo_rcut);
     ifs.close();
     EXPECT_EQ(atom_pseudo->nh,14);
@@ -75,7 +81,7 @@ TEST_F(AtomPseudoTest, BcastAtomPseudo)
         std::ifstream ifs;
         ifs.open("./support/C.upf");
         const double pseudo_rcut = 15.0;
-        upf->read_pseudo_upf201(ifs, *atom_pseudo);
+        read_pseudo_upf201(ifs, *atom_pseudo);
         upf->complete_default(*atom_pseudo, pseudo_rcut);
         ifs.close();
     }

source/source_cell/test/magnetism_test.cpp

@@ -17,9 +17,7 @@
  *      - and non-collinear case with nspin = 4
 */
 
-#define private public
 #include "source_cell/magnetism.h"
-#undef private
 
 
 class MagnetismTest : public ::testing::Test
@@ -34,6 +32,14 @@ class MagnetismTest : public ::testing::Test
     {
         delete magnetism;
     }
+
+    // Magnetism declares this fixture a friend, but a TEST_F body lives in a
+    // class derived from it, and friendship is not inherited -- so the call
+    // into the private helper has to happen here.
+    bool judge_parallel(const double a[3], const ModuleBase::Vector3<double>& b) const
+    {
+        return magnetism->judge_parallel(a, b);
+    }
 };
 
 TEST_F(MagnetismTest, Magnetism)
@@ -47,9 +53,9 @@ TEST_F(MagnetismTest, JudgeParallel)
 {
     double a[3] = {1.0, 0.0, 0.0};
     ModuleBase::Vector3<double> b(1.0, 0.0, 0.0);
-    EXPECT_TRUE(magnetism->judge_parallel(a, b));
+    EXPECT_TRUE(judge_parallel(a, b));
     b = ModuleBase::Vector3<double>(0.0, 1.0, 0.0);
-    EXPECT_FALSE(magnetism->judge_parallel(a, b));
+    EXPECT_FALSE(judge_parallel(a, b));
 }
 
 TEST_F(MagnetismTest, ComputeMagnetizationS2)

source/source_cell/test/pseudo_nc_test.cpp

@@ -21,25 +21,39 @@
  *   - print_pseudo
  */
 
-#define private public
 #include "source_cell/read_pp.h"
 #include "source_cell/atom_pseudo.h"
-#undef private
 class NCPPTest : public testing::Test
 {
 protected:
     std::unique_ptr<Pseudopot_upf> upf{new Pseudopot_upf};
     std::unique_ptr<Atom_pseudo> ncpp{new Atom_pseudo};
+
+    // Pseudopot_upf declares this fixture a friend, but a TEST_F body lives in
+    // a class derived from it, and friendship is not inherited -- so the calls
+    // into the private reader and the complete_default_* helpers happen here.
+    int read_pseudo_upf201(std::ifstream& ifs, Atom_pseudo& pp) const
+    {
+        return upf->read_pseudo_upf201(ifs, pp);
+    }
+    void complete_default_h(Atom_pseudo& pp) const
+    {
+        upf->complete_default_h(pp);
+    }
+    void complete_default_atom(Atom_pseudo& pp, const double pseudo_rcut) const
+    {
+        upf->complete_default_atom(pp, pseudo_rcut);
+    }
 };
 
 TEST_F(NCPPTest, SetPseudoH)
 {
     std::ifstream ifs;
     //set
     ifs.open("./support/C.upf");
-    upf->read_pseudo_upf201(ifs, *ncpp);
+    read_pseudo_upf201(ifs, *ncpp);
     //set_pseudo_h
-    upf->complete_default_h(*ncpp);
+    complete_default_h(*ncpp);
 
     if(!ncpp->has_so)
     {
@@ -62,10 +76,10 @@ TEST_F(NCPPTest, SetPseudoAtom)
     //set
     ifs.open("./support/C.upf");
     const double pseudo_rcut = 15.0;
-    upf->read_pseudo_upf201(ifs, *ncpp);
+    read_pseudo_upf201(ifs, *ncpp);
     //set_pseudo_atom
-    upf->complete_default_h(*ncpp);
-    upf->complete_default_atom(*ncpp, pseudo_rcut);
+    complete_default_h(*ncpp);
+    complete_default_atom(*ncpp, pseudo_rcut);
     EXPECT_EQ(ncpp->rcut,pseudo_rcut);
 
     if(!ncpp->nlcc)
@@ -86,12 +100,12 @@ TEST_F(NCPPTest, SetPseudoNC)
     ifs.open("./support/C.upf");
     const double pseudo_rcut = 15.0;
     // set pseudo nbeta = 0
-    upf->read_pseudo_upf201(ifs, *ncpp);
+    read_pseudo_upf201(ifs, *ncpp);
     ncpp->nbeta = 0;
     upf->complete_default(*ncpp, pseudo_rcut);
     EXPECT_EQ(ncpp->nh,0);
     // set pseudo nbeta > 0
-    upf->read_pseudo_upf201(ifs, *ncpp);
+    read_pseudo_upf201(ifs, *ncpp);
     upf->complete_default(*ncpp, pseudo_rcut);
     EXPECT_EQ(ncpp->nh,14);
     EXPECT_EQ(ncpp->kkbeta,132);
@@ -105,7 +119,7 @@ TEST_F(NCPPTest, PrintNC)
     //set
     ifs.open("./support/C.upf");
     const double pseudo_rcut = 15.0;
-    upf->read_pseudo_upf201(ifs, *ncpp);
+    read_pseudo_upf201(ifs, *ncpp);
     upf->complete_default(*ncpp, pseudo_rcut);
     ifs.close();
     //print