CI: Add single-header build

.github/workflows/ubuntu.yml

@@ -43,6 +43,16 @@ jobs:
       - name: build
         run: cmake --build build --target ${{ matrix.target }}
 
+  ci_test_single_header:
+    runs-on: ubuntu-latest
+    container: ghcr.io/nlohmann/json-ci:v2.4.0
+    steps:
+      - uses: actions/checkout@v3
+      - name: cmake
+        run: cmake -S . -B build -DJSON_CI=On
+      - name: build
+        run: cmake --build build --target ci_test_single_header
+
   ci_cmake_options:
     runs-on: ubuntu-latest
     container: ghcr.io/nlohmann/json-ci:v2.4.0

cmake/ci.cmake

@@ -581,6 +581,20 @@ add_custom_target(ci_test_amalgamation
     COMMENT "Check amalgamation and indentation"
 )
 
+###############################################################################
+# Build and test using the amalgamated header
+###############################################################################
+
+add_custom_target(ci_test_single_header
+    COMMAND CXX=${GCC_TOOL} CXXFLAGS="${GCC_CXXFLAGS}" ${CMAKE_COMMAND}
+        -DCMAKE_BUILD_TYPE=Debug -GNinja
+        -DJSON_BuildTests=ON -DJSON_MultipleHeader=OFF -DJSON_FastTests=ON
+        -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_single_header
+    COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_single_header
+    COMMAND cd ${PROJECT_BINARY_DIR}/build_single_header && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure
+    COMMENT "Compile and test single-header version"
+)
+
 ###############################################################################
 # Valgrind.
 ###############################################################################